I think the biggest problem with casino streamers is that nobody can guarantee whether what happens on their stream is legit. Correct me if I am wrong but I believe there is really no way to know for sure whether anything is rigged and the fact that the casino streams are among the world's best paid promotions for streamers and influencers make it only less trustworthy. Are they even playing with their own money? Does it matter when they lose 100k because they get 500k for a streaming night? I don't know, I don't find it particularly entertaining to be honest.
What matter to these streamers are they're earning money through promoting the slot and the casino. Plus it's a bonus if the players signed up using their provided affiliate link. For some of us, it might not convincing since we don't know if it's real. But for gamblers who got their attention (especially the newbies), these winnings are attractive and can lure them to gamble on the specific site, thus it's an effective promotion.
Therefore it depends on us if we're going to believe what we see and try it for ourselves if there's really a chance to win huge amount by playing slot.