People who lack proper knowledge of gambling are the ones that is supposed to make such mistake of spending all their money in gambling before they can realize their self but it's bad to see experienced gamblers making such mistake.
Poor people gambling with the little amount they can afford to lose and sometimes they end doing this similar mistake of staking all the money they had which will take a lot of time before they can get it back but the rich people usually have more source of income and they can usually gamble often because they have more money and even if they lose the one they had they can quickly get it back on like the poor.
Rich gamblers can also lose all their money as well as poor gamblers since they put a lot more on the line than poor gamblers. If a poor gambler can afford to put on the line $1, a rich gambler can put on the line $1000, or even more. In my opinion, it is wrong to compare which of them is more risky, because each of them has its own risk management depending on the financial situation. Besides, experience and luck have nothing to do with financial status. There are irresponsible gamblers among both poor and rich people.
Well, judging by the OP, why do the rich win more? The rich don't really have any special luck to win more compared to the poor gamblers, but the slime difference in that case is that rich gamblers always have the money to gamble continuously, and they can also stake a huge amount, which if they win, is going to give them a huge profit. But for most of the poor gamblers, they don't gamble all the time because of how small their pocket size is, and even when they are gambling, they play with a smaller amount than that of the rich.
You have already specified that the rich people can stake a huge amount more than the poor gamblers, but their losses are usually huge too, so the poor gambler will only lose the small amount they have staked.