There are people who think of making money by gambling and these people lose all their money by gambling and end up destitute. Because they continue to gamble to recover the money they lost by gambling, they lose all their money and they don't care at all. Losing all the money gets very worried. So the big people never get extra greedy because they take gambling as a pastime.
Yeah most people that usually gamble for fun are the rich, because they don't actually need the money that much and they are not eager to hit the jackpot. Most time some Rich people feel like they can do alot of things as they are wealthy, but so they always think of things they can't easily control , like for instance gambling which is base on luck, so they will take it as a form of entertainment to while away time , and putting some money on the line make it fun
Are you sure they don't need the money? They might need the money but they are not desperate for the money and they can live their lives well and happy without the money. Despite that, the winning from gambling taste differently and they will be super excited to hit the jackpot. Everyone love to be successful in whatever they do and that includes the rich gamblers. Therefore, they may not only be gambling for entertainment but to also win money because, like I said before, money from gambling might taste differently to them.