It all boils down to the discipline again. Your greed never should overcome your patience and discipline, because even if it comes from a good heart, it won't cause any improvement in the long run. There is a big difference between a gambler who sees it as a hobby and a way to have a good time and one who uses it to triple or quadruple his profit.
Even if the person is good at discipline, there is still a high chance of them getting addicted to the game if they consider it a hobby because they will turn it into something they will be doing almost every time they are less busy and are looking for something they could use to pass time. The more comfortable they are with it, the more likely they will get addicted to the game.