I play gambling when I'm bored and I want to have some fun, but I'm independent of this and I can stop at any time so as not to lose all means. Although sometimes I hope for a big win 
It is just a hard problem also when you have won a bigger amount. It will be another gamble all over again.
You will not stop until you double that profit of what you have already won.
If it loses again you will be using the deposited money until you lose.
Happened to me always. I would rather win small where I can stop than win big to just gamble again.
To overcome this, you have to control your feelings then only you can able to make money in gambling. Actually we will make money, but we don't know how to save that money. As you told our greed will not stop for one price. It keeps on making us win some more money. Becasue of this reason, many people will come again and play gambling. Our problem is if we win or lose we will not stop our game in time, so we lose more money.