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.
That is one of the reason why most of the gamblers are still preferring physical casinos, that is to have physical interaction with their friends, and the vibes that they could feel when playing is boosted if they also have drinks to enjoy. I just want to highlight that not all gamblers are violent when they are asking for drinks, maybe there are some that is frustrated because of their losses. If that is the case, maybe these gamblers who turns out to be violent could enjoy gambling at home, they can also buy drinks to enjoy playing without even hurting bartenders and creating chaos inside the casino.