I'd argue that after 25 years, he waited FAR too long for his hobby to somehow turn a profit and would probably be in a much better place now if he'd had gotten a real job a couple decades sooner. "1. Write a bunch of code. 2. Wait for money to flow in." is a terrible business model.

It's also the case that most open source projects just simply do not provide the value that their authors think they do. Think of all the paintings, books, and music ever written. Not the ones you've seen, I mean ALL the ones ever created by any human anywhere. Only a small percentage of what is actually produced ends up being good enough for people to talk about and/or pay actual money for. Software is no different. (And is in fact almost certainly much worse.)

I never want to be paid for writing code, that would take all the fun out of it. But I wish you all the best!