I often look at graphs of coins that mooned and envision myself buying low and selling high. Yet there's a reason why that never happens.
When we see a coin that's low, we don't want to buy. There's a recency effect. We think it's a loser. It's like if a girl sees you get rejected by other girls, of course she's going to reject you too.
Similarly, when a coin is exploding, everybody is singing its praises, extolling its virtue. The coin literally can do no wrong. It is a thing of beauty. It's been so good to you, baby, do you dare show your ungratefulness and sell? Of course not.
Suppose you do buy a coin that's low, and you watch miraculously as it pumps. If you believe in it, you'll stay loyal through minor hiccups. Then you can see its true potential, because you believe. But then, once it's peaked and everyone else can see that it's going to drop, YOU can't, because you have blinders on. You believe, and it's been good to you.
Now if you don't believe in the coin, and you see it pumping, you anticipate massive drops in every little dip. You become skittish and nervous, and you dump that thing at the first sign of trouble - and hence it never peaks for you.
To sum up, when a coin is low, there is massive inertia - you don't want to buy. When a coin is high, you're literally intoxicated with giddiness - you don't want to sell. If you believe in it, you'll watch it peak and then you will get disappointed by it in the end. If you don't believe, you will get rid of it much too early and never see it moon.
So remember that you can never win at this. These are fundamental forces of nature that conspire against you. It's a rigged game. It's impossible to just "buy low, sell high." So what do you do? Well, you do the exact opposite. You buy high, and you sell low.