I have never seen a statistic that says the poor win lesser to the rate at which the rich gamblers are making winnings, we don't even have a data to differentiate the numbers of the poor gambling to that of the rich gamblers, all we know is that people are gambling and are winning as well as loosing, and this is not because of their Finacial status or background, everyone has equal right and ability to either fall under the same category with other gamblers for loosing or winning.
you are right that there are no statistics like that, maybe the OP is a poor gambler so he often loses. He might also compare what he saw a rich streamer and influencer gambling with big bets and then they win big, that's why maybe the OP said that Rich gamblers win more, even though influencers and streamers actually bet big money because it is funded by casinos that collaborate with casinos so that every game played will be easy for streamers and influencers to win because everything has been arranged as part of the campaign.
Even though rich gamblers never gamble like poor gamblers who usually play all the time, most rich gamblers only play at certain times and even with money they are ready to lose so they know when to gamble and stop gambling, so OP could see when they they win and they don't when they lose, after all, rich or poor gamblers are all the same who have won and have experienced defeat, it's just that most rich gamblers see gambling as just entertainment, which is different from poor gamblers who always think of gambling as a place to make money, that's why they often gamble in gambling hoping to win.