Cause it's true. Rich people have more instances to play in casinos due to being, well, rich, so it equates to more chances of winning and equates to them winning more compared to the poor. On the other hand, the same could be said about losing though since they lose more compared to your average joe. The difference is in almost all cases, they can afford the loss. And maybe even 10x more of that with still room to spare. Unlike most low-middle-class gamblers who spend everything, including money for their basic needs.