I can not control my greed in gambling, because I want all at once and more. Because of this, first I lost a lot of money 
It is same for majority of gamblers, many end up losing all they have won while playing. I have also seen one guy who won around 100BTC in a dice site with just a deposit of 1BTC and successfully cashed it out. But due to greed he came back on next day and lost all those 100BTC + 30BTC from his pocket. 
This is a typical situation which only proves that gambling can't make you rich. I even think that when people lose they are in a better situation because the probability of their return is lower. This doesn't apply to gamblers who play for fun only and lose only what they can afford to lose.