> that I would change the world or use my degree to do anything meaningful.
You do not need to change the world to have a fulfilling career. Here you should think selfishly. If your job works for you then it is okay.
I do not feed african children but when I'm at the office time usually flies because I consider what I do to be entertaining for me. It keeps me focused and it keeps me engaged and that is all I need to feel like I'm not wasting my time.
> we're just a cog in a larger machine
True but this is not inherently bad. Here is where it serves to separate your identity from your profession. You do what you do to get money and as long as your job is not killing you from the inside then you will be fine.
Furthermore, no one is stopping you from starting your own business. Free market.
> we're replaceable
True but such is the nature of competition. There is also nothing inherently wrong here. If you are at a company then you already have experience in dealing with the specifics of that company so you will be preferred over someone from outside unless you majorly fuck up.
>doing the same thing over and over again
This is why you study something you like doing over and over again, which is why you study STEM.
Furthermore, companies are not static. Projects come and go and the specifics are always different. There is always something new to do in STEM jobs.
>but once you hit 40, that's it you're locked in.
Not necessarily and this has not been the case for many people, Nothing ever stops from moving forward.
>if you aren't management you're a grunt
Then that is a really weak definition that basically means nothing. Furthermore, the company I work at doesn't even have set managers. There is literally no manager structure. This may be a quirk of smaller software companies but it is still true.
I do not hate my job, I'd even say I like it very much.
It helps that I've literally wanted to work in software since I was like 15 and I made it.