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.
Without blaming anyone, I will stop if I realise that I am consistently exceeding my bankroll and losing alot of money which is beginning to have a negative effect on my mental health and my general wellbeing. Yea, there is no motivation anymore to gamble further, so it's best to do the right thing before it's too late.
Even with this reason to stop, quitting gambling can be one of the toughest decisions to make for some gamblers. Especially gamblers who have won before and are still trying to win again or for gamblers who have already lost alot and are trying to recover some or all what they've lost.