I think a lot of those youtubers from the period didn’t want to be youtubers. They never had the understanding of what life would be like doing it as a career, and it’s surprisingly un-fun and tiresome. But the money is good enough, and they have freedom, and after years on youtube they’ve basically burnt through all their chances of regular employment anyway, so they just keep at it.
Seems to be the cycle for those few early 2010’s channels that have stuck around. They continue the grift just to keep their fanbase on life support because it’s all they have. Newer stars getting into it FOR the youtube lifestyle maintain their enthusiasm better because they know what they’re getting into.