As the questions says, when do you stop? your point of no return?
a. at least double your money, then stop
b. you only stop when you have lost all your bankroll money and then blame the casino?
c. or you are a superstitions gambler, when you have signs like losing 3 straight in a row, then you quit because you know that you're having a bad luck
d. you stop when you are at least break even
I didn't include chasing your losses as obviously you might to continue.
I stop when option A and B happens to me. Though for option B, I don't blame the casino after I lose my bankroll. Doubling my capital rarely happens for me when gambling so if I have the chance to achieve it, I withdraw immediately to safeguard my winnings.
While stopping when your capital has run out in gambling should be a normal discipline to any gambler. It's important we hace that rule to prevent us lose more in gambling.