So once a streamer got a deal with a casino (for sponsorship) then there is no chances for him to participate in any contests in the casinos even if the streamer want to use his own money for the contest?
I doubt they will participate when they already made a deal with a casino. The reason only because they want to get huge attraction from people who seeing they playing on that casino, so more people will be wager more on that casino because of they showed it. That's main reason of hiring a streamer IMO