I experienced that many times when working in casinos, gamblers explicitly asking for more drinks, and even getting violent if you refuse.
When they are drunk, they can use violence to force the bartender to give them more drinks. They said that they need more drinks to make them focus on getting the win. But that is what happens in the physical casino, but we will not get that experience on online gambling because we never meet with the drunk gamblers.
Most of the casinos have high security system where you can find guards everywhere, its not a bar or club so people who seems misbehaving will be kicked out or even will be completely banned from playing in that casinos.So the people who get violent with any workers unless they wagered huge amount in that casino have high chance of getting kicked out.