Theirs nothing like gain in gambling, what is actually happening in the gamblling is grace to succeed, talking of greediness is happening directly in gambling, because i know that some gambling like casino and poker game their is nothing like greedy because as a gambler you have your own target of getting what you want in gambling.
It is very difficult to make a profit from gambling and not many people can get it, but it still makes people keep trying.
And yes, if we win a few rounds, we will still keep trying to get a few more wins and that causes us to be greedy.
All gambling games are designed to give us the temptation to keep playing, whatever the results we get.
And if we don't realize it was a mistake, it's only a matter of time before we will suffer a major defeat.