I’d be interested to see an example, because I’ve never heard of any, and some of the most prominent players in the world (eg Daigo) have day jobs.
I’m pretty sure FChamp doesn’t, aside from playing videogames. From what he’s told us, he can make enough off tournament winnings and sponsorships. It’s all a matter of being good enough to take the pot at every tournament (major or minor) that he goes to.