If you are gambling for money, you will easily be able to decide stop gambling when you win a big sum. You may also stop gambling with a very huge loss. But when you are a gambler who is gambling for fun, it will be another reason, something apart from a win or loss that will stop them and make them quit.
If you gamble for fun also and you win big It is possible that you change your fun activity to something else because you can now afford more.