Depends. I’d say for example that the primitive technology channel does it out of love. So there are people like that, even if the wast majority does it because let’s be honest a career in video gaming sounds great. But the thing is those are also the least likely to attract viewers.
Top spots nowadays are claimed by sponsored players anyway and making it as an amateur is nightmarish difficult. Fame grows exponentially because once a talent emerges companies are quick to sign it up and after that they provide most of the promotion for their talent to grow.