I think you should determine on how much you have to win to stop. Because if you don't know how much or you don't have an idea when you should stop, this is going to the point of addiction.
Winning millions with gambling is a very rare case, I would actually quit if that happens to me although there were gamblers that experienced this. I wonder on how they're doing right now.
I feel setting up a target reward to win from gambling will make us more addicted,so just play and enjoying the moment will keep the things simple and also avoid gambling thougts in our daily life routine.Winning millions is rare case but I never seen anyone left their gambling habit even after they won in millions,they will spend all the money for betting in the process of making billions so quitting never related to the reward amount.
You have the point on that thing but I think it's not about of being addicted through setting up a reward. It's the two way around, if you are lucky on that day and you keep on winning, you have to set up for the minimum or maximum limit of winning.
And if you're unlucky, you do the same thing, setting up the minimum and maximum amount for stopping.