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 am not a frequent gambler, that is, I don't gamble all the time and when ever I choose to gamble, I usually make sure to set money aside for it, the amount I choose to set aside will depend on the amount of money I can comfortably afford to lose at that particular time, lets say for example, I set $40 aside to spend on gambling, when I start to gamble, three things can make me to quit and possibly not return anything soon.
1. I win a large amount of money, I will stop and withdraw because if I keep playing, I might lose it back to the casino.
2. I lost all the $40 I reserve for gambling, I will quit and wait till next time when I feel like gambling again.
3. I lost interest in the game half way due to one reason or other, for this, I might return the next day to continue playing so long as I still have enough balance left, but I quit soon as I lost all the money without any win to keep playing further.