Maybe when you have surrendered and accepted defeat, you can conclude that gambling is entertainment. Of course, everyone hopes to win the bet. If everyone thinks gambling is for entertainment, of course gambling will only be done by people who have a lot of money, while the enthusiasm of most people, gambling is more popular among the lower middle class. This is because many people try to seek fortune from gambling.
It's true that a higher number of profit/fortune seekers have dominated the gambling space, and majority of those gamblers having to fall under the poor and middle class, but that doesn't in anyway prove that entertainment mindsets do lead to losses, does it?
Whether rich or poor, everyone has their various motives for gambling, there are poor gamblers who gambles solely for fun and there are also rich folks who turns to gambling as a means of escape from debt or financial challenges. It's just a matter of mindset and not really about financial status.