You've forgotten about the effect of investment. Work on a team doing contract early-stage development for funded (that's important) startups and greenfield "experimental" projects for larger corporations and you can work on four projects in one year, zero of which ever see enough ROI to pay back just your personal pay. And then do it again the next year.
The end result is that you feel like a tiny part of some weird, random, extremely expensive process to (rarely) create successful new businesses. Like part of a living pachinko machine that burns cash. But you can get paid plenty for it!
> earn some reasonable money
These two are in opposition