So my question is, is the percentage of the rich gambling lower than the middle and lower class?
One thing you should know is that gambling is a choice, it doesn't determine who you are, your level or class wether higher or lower. The lower class keep on gambling hoping to win big someday and be like the higher class. While the higher class gamble to win bigger than his current financial status because human are insatiable which makes them not satisfied at any given time. the quest to Wealth is endless, otherwise people like Elon Musk would have stopped hustling.