Let's not generalize but somehow there are people who's earning a living in gambling, Don't forget we have have pro poker players who earning a fortune by playing, read the article here
https://upswingpoker.com/top-ten-best-poker-players-history/ but this is a skill based game though. But if we talk about luck based game then I will agree with you and even popular streamers cannot get a continuous revenue by just solely playing.
Yeah I think a lot of people are misled by the numbers. Yes, there are streamers earning hundreds of thousands, or even millions, but most of these are just sponsorships that won't last forever. And trust me, in general, they put a lot of it back into their gaming. It's not going to be sustainable for a lot of people. Can't ever generalize anything, and very few people realize that only skill gets you a job in the end.
Poker is a totally different thing, every single hand is legit equal between all the gamblers there and it is all based on how talented you are to actually end up winning that one, if you are really good you could actually make it work however that is something all equal to everyone, house doesn't get involved at all you can take all the money other person has and as long as you are a good player there is nothing stopping you from doing that.
Regular luck based is not like that, it is based on house edge which means when you win you get 99 but when you lose you lose 100 and that 1 difference is literally the reason why you can't continue to gamble forever and still make a profit, obviously you can get lucky in few bets but it is not sustainable forever as an income. Streamers are different because they do spend money on gambling but make it back and more from streaming income.