It's actually near impossible for someone watching to determine whether the person who is playing online casinos is paid to do so or doing it from their own money. However logic dictates that there would be a tiny amount of genuine players, who are funding it themselves as a "hobby", are actually running these sort of channels. Poker sites are probably the exception, because there is a genuine level of skill and talent involved in this game, however even that can be rigged in many ways if the intention is to draw in new players (showing a higher number of wins than you might expect). However streamers putting out content where they just play slots all day should be considered highly suspicious, frankly I don't know how anyone finds them interesting.