Pay like other things is something you mentally calibrate to. Once you have then it has only marginal impact on your happiness and mental well-being. Let's say your TC is $120k or $80k or even $250k you're going to adjust your lifestyle to this. So sure, you can drive a nicer car and live in a nicer place for $250k but now you also maybe have to make payments on your nicer car and your nicer house and those things may not make you any happier.
Not everyone in the world is doing it - because not everyone can do it and not everyone is motivated to get to the point where they can do it, even if they could.
I live in the US, and according to what I read online, I am severely underpaid. The thing is, I don't really care. I have almost 9 years of experience, and I haven't even broke $100k yet. I work in government (state level), so it's not known for being high paying in the first place. There are other benefits, of course.
Nonetheless, I would obviously take more money, if offered, but I don't feel the need to frantically run around in the rat-race for it. I seriously cannot imagine what more money would do for me. I already feel like I make plenty just to push buttons on a keyboard.
I got my first software job while I was still in high school and when I started my career I mostly worked jobs that I really enjoyed for a lot less than I could potentially make otherwise. I didn't have a family yet, I didn't have a lot of expenses, I didn't care. Later down the road I joined a "real" startup and started getting paid much better (coincidentally or not around the time I had my first child) and since then I've sort of been in the rat race so to speak. Can't complain though but most of my later jobs were not as fun as my earlier ones.
Not everyone in the world is doing it - because not everyone can do it and not everyone is motivated to get to the point where they can do it, even if they could.