With the particular games you mentioned, you could also argue that rich people prefer more 'visible' games while the poor prefer 'invisible' games; Blackjack an

With the particular games you mentioned, you could also argue that rich people prefer more 'visible' games while the poor prefer 'invisible' games; Blackjack and roulette are done on or around a table with (possibly) many participants, whereas slots and lotteries are aimed to be a one-person experience.