we cant guarantee that we will always win in gambling ,however when we win we must consider to control our emotions and not get too greedy so we can make a profit out of gambling.
I guess we are talking about typical casino games like dice&roulette in this context. Since, for example, in poker there is no need to "stop" because if you keep winning its usually linked with the fact that you are playing well and have the edge in the game (obviosly, not always, but most of the time). If you listen to the Phil Ivey's interviews, he always says that if he feels that he is playing bad, and losing, he can stop the session pretty much instantly, but if he plays well and keeps winning, he will not leave the table for hours, and even days.
In dice though, it depends what your initial goal was. If the goal of your session it to get some profit and locked it up - its obviously pretty retarded to keep pushing your luck. But a lot of people roll the dice for whole other reasons, and they wont stop just because they won something, its their choice too, and nothing wrong with that.