Remember in gambling, "a winner is the one who knows when to stop". If you keep on betting based on your previous wins than you are deemed to loose that all one day. Its very hard to stop betting when you are winning and thats why gambling is banned in some parts of the world that it usually take people to debt.
I agree, only a handful of people can make a living out in gambling, those people are good in numbers but if you are just an average joe, you will win sometimes but in the long-run the losing streak will get you if you dont stop.