In simple words if you can't control over emotions being greedy while gambling then you will lose your money right?
True and its also true for all risk based reward systems. For example in trading and binary options the site will capitalize on your frustration and greed. Its how they will make money and you have fight it.
But yeah it is pretty hard for the people who are doing gambling for the sake of money so let the gambling for it supposed to be not for making the millionaire.
Some people think they can beat the house - but thats fake confidence without using logic. If they would be rational in their decisions they would not gamble to be a millionaire. There are other ways of becoming rich but gambling for most will be a waste of time and money if they cant control themselves.