Because of the difference on bankroll. Rich people have a huge bankroll that gives them freedom to increase bet or play more until they win huge amount while poor has only limited bankroll which they will stop immediately once they lose enough.
This is the reason why poor shouldn't play gambling because it was intended for source of entertainment not a way to escape poverty. Bankroll is very important on gambling to stay longer until you hit your streak to profit.
That is what I want to say that the difference in bankroll can also judge, because with a large bankroll the freedom in gambling will increase their profits are also large if they win the jackpot and the rich do not despair if they lose because they have a lot of money reserves so it will not be pressure or stress for the rich.
Poor people with minimal bankroll always hope to win with little capital, and the only victory in gambling is always the hope for their lives, so this is the wrong way when the bankroll is small especially not for the pleasure of gambling then until whenever they will still lose even if lucky but it will not be as big as the capital spent.