My impression is that many of these "open source developers" overestimate the value of their code. There are many amazing projects for which I would pay considerable price, but the long tail of 99% of projects just aren't worth anything in my opinion. It is an interesting exercise though - to imagine how much I would pay for my window manager, gcc or even Vim.

Maybe easier transactions of tiny sums is the real solution? Even if every user paid something trivial like 10 cents a month, it would be a huge revenue stream for popular projects which lack maintenance. Of course, adding monetary incentives opens a whole new can of worms, so maybe the current situation is the best we can do after all. I suspect that many good qualities of open source software come from lack of money involved - there is no telemetry, no dark patterns to keep you using it, no attempts at vendor lock-in.