There was a really good article about this (wish I could find it) about how the majority of these aren't making much, if any money. From the outside it appeared that the artists are rolling in cash; from the inside, they were still working waiter/waitress jobs to make ends meet.
Yeah I heard from one YouTuber (over email) that only ~1000 worldwide are currently making a living solely from their YouTube career. And that includes certain successful channels that employ 20+ people.
