Absolutely ridiculous to assume that only some careers allow the makers to live off them.

That's the point: for almost everyone it's not a career. It's a hobby. Like some people have a career researching physics because they're extremely good at it and society has decided it makes sense to have a few. Then there's people like me who learn what they can of it in their free time, but I do something else as a career because realistically very few people have need of someone who's familiar with the Dirac equation or whatever. Among the general population I'm probably in the 99th percentile of math/physics knowledge/ability, but I don't do that for work because we don't need 1% of the population working on such things. And that's for a skill that causes most people to get anxiety; the demand mismatch is probably even greater for things that average people actually enjoy.