@cks For kernel I wouldn't be surprised if the vast majority of ones in the maintainers file are paid for their work, in fact I feel like Linux Foundation should at least provide some funding to them.

And I kind of feel like hobbyist open-source is a cockroach, and all the "open-source is aging" things I've seen so far seem seriously subject to sample bias and more that the rock stars maintainers and their social-circle/community are aging.