if I were rich, I'm not going to gamble. I will use my wealth for more useful things and go on holiday with it to get pleasure
And don't forget to make more money out of that money!
Because anyone may get broke by just spending money without an income.
That is a completely different topic whether rich people should invest or just sit idle. The thing is that he will not gamble if he was rich that means he is gambling for money and that is not a great sign from a gambler. In my view, anyone can gamble but should not invest more, like that could change his status from rich to poor.
That is tantamount to saying that only gamble what you can afford to lose, rich and poor are completely in a different status so if a poor gamble an amount that is big enough for him that it could his life regardless of the result but maybe for the rich it is just an immaterial amount to him and he can stand if he lose his bets. That is the big difference, rich has the financial freedom.