How common are various levels of adventurers?

Depends on the game, of course, but assuming 3rd Edition D&D, not very. Even in a major metropolis of over 25,000 people, folk with PC class levels only make up about 15-20% of the total population at most. Of those, only a handful (maybe 20 or 30 people) will be 20th level. There will be twice as man at 10th level, twice as many of those at 5th level, and so on down to 1st level.

And that's for the huge metropolises. At town level most adventurers don't hit even 10th level. Small hamlets and thorps have a statistically likely chance of not having any adventurers at all.

I hate to point this out, but this is pure theorycrafting. You realize that, right?

Most places don't have tens of thousands of soldiers immediately on-hand to deal with problems.

30 people at 20th level sounds like a lot. Like, that's reality bending god-king tier, even for martials.

Level 20 martials are kings, can move one space but threaten anything around them, assuming they're allowed to do so.

Level 20 casters are queens, can move an unlimited amount of spaces, can travel in any direction they want, and have full control of the board the moment they're in play.

So 30 Level 20 Fighters wouldn't really break reality that much since they're still limited by their inability to affect much outside of numbers on combat while 5 Level 20 Casters would practically rule the world and be researching ways to go beyond Level 20.

There’s significantly more than 30 level 20 casters in any d&d setting it’s judt they all fucked off to unravel the secrets of the universe in seclusion. They live on the planar edges or in a pocket dimension of their own creation, or perhaps a full plane they created. They observe the outside world sometimes but they don’t really care. Who gives a shit about world domination when absolute knowledge is within reach? Just a few hundred more years and they will know...surely with time will come understanding...surely...

>How common are various levels of adventurers?
I like PCs to be exceptional characters - as in there aren't really 'adventurers' as a job or class of people that occupies the same landscape as say a knight or merchant. I prefer classes and levels to be strictly part of the metagame without having any reference within the secondary world.
But I'm afraid your premise of this dragon slaying army is; in my opinion; fundamentally flawed. Lets take a look at the logistics of such an operation...

You can't just 'hire' skilled hirelings for 2 gp a day for a max of 2000 gp each day and be done with it - that 2 gp is not covering their expenses - that's their pay for joining you and willing to fight.
>Crossbows and Missiles
I'm not sure where the range of '320' is coming from, so I'll just price up both the hand crossbow and the heavy crossbow.
Hand Crossbow: 76000 gp (1000 hand crossbows + 1000 Crossbow Bolts)
Heavy Crossbow: 51000 gp (1000 heavy crossbows + 1000 Crossbow Bolts)
This should just be a one time expense, but these guard level mercenaries are not going to walk out into battle against a dragon with just commoner's clothes armed with crossbows and ammunition.
>Miscellaneous Equipment
A Medieval army brought a lot of things with them, especially if it was on the move - but I will simplify it to D&D terms as I both do not have the whole width and breadth of knowledge on the topic and things need to be kept relative for game terms.
A guard has a chain shirt and shield for armor, that's another 60000 gp, and on the fighter's equipment list it states that you'd start with either a dungeoneer's pack or an explorer's pack - lets pick the less expensive and say the explorer's pack - which is another 10000 gp. That's either 146000 or 121000 gp so far.
But this is just starting equipment, the things that this army is not going to be consuming every single day.
Cont.

In 5e, it describes the lifestyle expense of Poor at 2 sp a day, and mentions that mercenaries would probably be living in these conditions, so we'll take that as the money spent to purchase food and water. It also describes that a person must consume 1 pound of food and 1 gallon of water a day or suffer exhaustion.

That's about 200 gp per day for the soldiers alone - but where are they suppose to get the things that this gold is paying for if they're on the move?
A supply wagon of 50 mules with 50 carts carrying 1000 pounds of food and 10000 pounds (1000 gallons) of water, manned by 25 unskilled hirlings (drivers) costs 1155 gp as a starting cost, then 5 gp and 20 cp each day for the living expensies of the unskilled hirlings. This only gives the army a range of 18 miles, since 24 miles is a whole days trip at a normal pace - and this would have to be multiplied if it was going to be further away.
>Total Cost of A Dragon Slaying Army using 1000 skilled hirelings armed with either hand or heavy crossbows
Upfront Cost: 147155 gp or 122155 gp (Weapons, Ammuntion, Gear, and Logistics)
Weekly Cost: 15471 gp
Monthly Cost: 61884 gp
A band of adventueres isn't going to have to cover all these costs (mercenaries and soliders often had to buy their own equipment, and armies did often simply plunder the area they occupied for resources), but there is no such thing as a free lunch - all this stuff has to come from somewhere, be manufactored into useable goods, then paid for. And this is going to be coming from a kingdom that has been under attack by an powerful ancient dragon that is far more mobile than a standing army of 1000 guards could ever hope to be.
As a side note, the average dragon's horde (not factoring magic items) holds 322000 gp - which would only pay for 3 months of this armies expense assuming the dragon's horde is 18 miles away from the kingdom.
If my math is off or if I've missed something critical to this strategy, please let me know.

I think you should run a simulation of 261 level 1 fighters against your gold dragon and see what actually happens

Guard "creatures" in the manual explicitly comes with chain mail, shield, weapon and ranged weapon.

I would presume that a guard is a skilled hirling who comes with the equipment they need.

And I would presume that a kingdom or empire has an army already.

Furthermore, the cost of services list spellscasting cost as Caster level × spell level × 10 gp so you could hire a wizard to cast teleportation circle for you for a mere 1530 removing the need for most supply and and transportation.

Loot its lair then. That is like to get it come running. And when it does just tell the nearest guards to jump onto it and hold on for dear life. Creatures can only fly with light loads so even for an ancient dragon that is only a few guardsmen before its grounded.

Or just simply teleportation circle into its lair when its sleeping

Why would the Kingdom raise their army to fight a dragon, to which it doesn't often deal with, and the losses would be extreme, when they can just get you to do it? It still costs just as much money, whether or not you are spending it.

Plus, if you really wanted to be obtuse, why aren't there bands of wizards teaming up and teleporting in and stealing everything in sight on their own? Why aren't there dragon armies that absolutely raze and destroy everything on their own?

Because the setting doesn't allow for it, jackass. The rules aren't the end all for this shit. The DM is. The rules are there to simulate reality, or at least, this world's reality. Once you start breaking it, the rules get thrown out the window. Stop being a that guy.

But good stuff tough.

Cause adventurers cost a lot of money to hire, what with rewards an all, why not use your standing army you are paying and supplying anyway? And 40 men (given that you spread the 100 men evenly in a 320 foot radius) is not exactly extreme loss.

Oh, and because level 20 adventurers are extremely rare but the common soldier is not. Perhaphs they don't want to wait for a party to wander in.

Feudal systems don't have standing armies and what soldiers they do have that can be raised easily have their own lands, families, and are often administrators of smaller communities. It is great economic upheaval to go to war. Also, losing 40% of your force in a battle IS a great loss, considering the attrition rate matches how many you lose in battle most often, which is pretty much 10% most of the time.

You know nothing about medieval tactics or lifestyle, only obviously broken rules, so why continue to try? We all know the system is garbage. But at least it simulates something. What are you trying to achieve here?

So you're telling me that every single Level 20 caster in existence decided to fuck off to explore the universe? Not a single one decided to go "eh, y'know what, I have ultimate power, let's go ahead and warp reality to suit my own ends" or something like that? I mean, where are the fucking necromancers who decided to become liches?

The reality is that even the writers for D&D cannot justify a semi-medieval setting in which the most powerful mages didn't usurp every kingdom's authority in some way, so they all shunted them off to parts unknown so that PC's still had some reason to exist and why monsters are still allowed to fuck shit up.

I feel like your forgetting the fear aura that comes with larger dragons, presuming 5e, a save of 24 in 120 range which a lot if not all of your soldiers will fail. It can also shape-shift to a smaller creature so you can't guarantee your hired helpers will even be able to shoot it.

So the dragon can just wait in its lair or some other enclosed space and just never worry because your soldiers will never be able to fight it.

See that's the thing. Most of the guys who wanted to influence the world, they end up dead.

Liches are 18th level spellcasters. They're not level 20. The ones that ARE? They fucked off to explore the universe. Who gives a shit about the material plane when the secrets of creation, the fabric of fate, can not only be seen, but potentially interacted with given enough time and determination. Eventually perhaps, they could be gods if they wanted.

Most don't, most are driven by curiosity, ever expanding, ever demanding curiosity, and have no time and least of all care for what happens outside of their need to sate their thirst for knowledge.

>See that's the thing. Most of the guys who wanted to influence the world, they end up dead.
Not the ones that are smart enough to do so over a period of time. We're talking about an individual who is smarter than most people and has access to magic and the ability to become effectively immortal.

A charm person here, a simulacrum here, a divination here, and suddenly you have a being who is practically illuminati levels of control while setting up enough proxies to make it so that none of it is directly traced back to him until it all begins coming together.

Like so many people write these omnipotent casters without really taking a moment to think of what a Level 20 caster with 20-30 INT and centuries to set up shit could do and how that would (or at least, should) change the setting over the course of a few generations.

Also, you're telling me that literally every wizard decided not to pursue power? Even the Evil ones? It feels like a copout honestly.

>not setting your campaign in ancient china

I think the argument is

>Why should I care about ruling your shitty little city-state, when I'm researching how to create my own demiplane and a whole new race to populate it with?

>Why would I want citizens to answer to, when I could create worshipers?

>I've drank and eaten all of the most exotic things, fucked the most succulent lovers, seen every beautiful and horrible sight, danced to music that moved me to my core, and otherwise experienced everything this world has to offer. The bureaucratic nightmare of governance doesn't exactly appeal. Been there, done that.

>I wonder what the Elemental Plane of Sex it like this time of decade.

Again it’s not a matter of inability it’s a matter of not wanting to.
The evil ones who want to rule the world? They’re the ones who are the BBEG your party gets to stop.

What about the evil wizards who weren't Saturday morning cartoon villains who come up with convoluted plans because "no way they'll find a way to overcome my genius?"

Because the way I see it, an evil wizard with 20 INT and multiple ways of attaining immortality should, in essence, be smart enough to play the long game and take over the world long before the supposed heroes even realize what's going on.

You're blaming bad and or lazy DMs for that.
Don't forget, there's other 20 Int wizards out there to oppose them and foil their carefully laid plans.
Nothing happens in a vacuum.

>Don't forget, there's other 20 Int wizards out there to oppose them and foil their carefully laid plans.
I thought every wizard was too busy collecting magic mushrooms from the mushroom plane or some shit like that. May I refer you to As long as they don't interfere with their own bullshit, I don't see why they'd notice or care.

I think OP is implying 5e, which has morale rules in the DMG. Like a true theorycrafter, he will ignore that which does not benefit him however, and treat everything as a pure numbers game.

most of those things have enough damage resistance that they are more or less immune to mundane mass production weapons

realistically, that army of 1,000 guards WILL route pretty quick. Believe it or not, getting paid is not really a good motivator to stand there and get flambe'd. Plus, this ignores the fact that Dragons have absurd intelligence and magic abilities, and likely wouldn't fight unless it was a trap in the dragons favor. This also ignores the fact that most of those guards won't even HIT the dragon since AC doesn't scale well, let alone dragon- even if every guard rolls a successful dex save, and the dragon rolls 1/4th normal damage on its breath attack, the dragon will probably still kill every single person in the cone of death.

Now for the tarrasque, the tarrasques sheer HP regen will probably keep it going far longer than it "should", in addition to the fact that the Tarrasque is an utter slog even for level 20s due to its absurd HP, magic resistance, AC, damage reduction, and regeneration.

Again, the dragon is far smarter than the average man--even the dumbest adult dragon (White) is far smarter than the "average" man. Something like a Red dragon or Gold dragon is basically born with einstein-tier intelligence, and it grows from there. NEVER underestimate a dragon--if it is fighting you, either its a trap or you managed to corner it/catch it asleep in its lair.

this. I bet Godzillas damage reduction is over a hundred at least, if not hundreds. Puny mass produced iron arrows won't do jack shit

I like to think this is how most lichdom starts--just sloth taken to such an extreme that death itself seems like an inconvenience, to say the least of hunger and sleep. at some point, its easier just to abandon all trappings of mortality and be so terrifying that everyone just stops bothering you, and then you set up traps and horrible monsters so adventurers die before they bother you. Then you have all eternity to just dick around and green-light whatever magic experiment or game you want.

20 int, not level 20 wizards.

For every level 20 wizard, there's 500 more at varying levels of skill at LEAST.

1 lb of food sounds a bit low to me tbqh, especially for manual laborers. I'd say you'd need to double or even triple that to maintain any degree of modern nourishment, particularly for mercenaries or soldiers who have to maintain a much higher physique than a tailor's apprentice or something

You can make the same argument for 1000 peasants vs. one adult dragon and the outcome will still be the same.

Level 9 spells only need one spell slot for a damn good reason, plus there's also the temptation of a lowly acolyte learning high level spells from a Dark Wizard in the mood for peons and proxies.

another caveat is explorer experience. A level 20 party would have the resources to feasibly learn what a dragon has up its sleeves; pretty much any level 20 adventuring party (particularly those with wizards/bards) would have a large body of knowledge to warn them about any tricks or aces up their foes sleeves. A group of 1000 guards may have fatal misconceptions about how to fight dragons, simply because their knowledge is much poorer. Perhaps they think a red dragon is vulnerable to burning sage, or can be forced to reveal its true form if exposed to powdered cinnamon or silver--and in reality none of those things actually make a damned bit of difference. Countless man-hours and gold may be wasted pursuing old wives' tales or superstitions that may be an active detriment to their fighting capability, whereas an older party will have much greater luck in finding the right combination of gear/tactics.