Once you've identified the problem as "greed" you should be able to tackle it by being satisfied with what you have or what you get from gambling so that you don't keep gambling even if th odds and luck start being against you. So I will recommend self discipline and the ability to know when to stop and be satisfied.
well that's the hardest part mate, knowing when to stop and discipline your self since greediness really eating you up every time you think that you are lucky, maybe limiting yourself and make some awareness that there's certain amount to target or certain percentage to place win or lose you needed to quit.
It is very hard for a gambler to control themselves when they are addicted and it is easy to get addicted to gambling. Usually gamblers are so concentrated on the winning outcome that they do not foresee the fatal losing outcome and that's when they lose control and begin to lose. Setting a limit also doesn't help if you are addicted because you will find an excuse to keep gambling to see if you can get more out of the game. Gamblers should seek help to prevent the leisurely activity from manifesting itself into a huge problem.