There are many reasons that came to my mind as to why I will quit gambling.
1. Priorities - When I say priorities, I mean those important things in our lives that needs to be bought. Family expenses, bills on the house, etc. Right now, it's still not happening, but I know there will be a time, and if that happens, I might quit gambling. Right now, I'm still gambling, and I'm happy doing it while spending a few bucks.
2. Lack of money - Obviously if you're out of money, you will not gamble hence, you will be quitting gambling. If you don't have money that can be allocated into gambling, you will be forced to quit it. This is the problem when you're poor. You don't have any money that you can use for you to be entertained.

There are still other reasons for me to quit gambling if needed, but those 2 that I shared are the ones that came to my mind. I'm pretty sure that everyone here has their own reason as well. What's important is we are enjoying ourselves while gambling without spending too much money on it.