For the rich and wealthy, gambling could easily be something done out of fun or leisure but, when it comes to people who see it for a means of earning there daily bread, it easily feels like an only chance or means to a survival.
Sorry if I didn't get this right, but are you suggesting that reach people are more immune for addiction? If my interpretation is right then I have to disagree with what you said. I don't have exact numbers but I believe it's actually the opposite which is right. Wealthy people are more prone to all kinds of addiction not only gambling addiction. They spend more time playing because they can afford to do so which makes them subject to addiction and they won't realize it till they start running out of money.