Story about that. A while ago I sent a $$ contribution to an OSS author who'd built an app I liked for Linux.

He wrote me back. He said mine was the only donation he'd got in the past 2 years.

That's the life of many OSS authors. And yah like you say, the top programmers can go get 1-300K's of dollars or euros or w/e working for big tech.

Many core linux contributions in the kernel or w/e do come from highly paid programmers at big tech co's. So there is that. But run of the mill programs and apps that are still useful day to day, many of those are done for no money.