earn in gambling? no one people can earn on that,gambling is like addiction on drugs if you do not stop they destroy you!! yeah you will win but in last they loose your money, not only that everything you have we will lost if you do not stop.. its hard to win on gambling 
Basically you can earn something when you have a luck and you can control yourself after the luck. Most people lost all their money after after a winning was just because they were too greedy.
Yes you can earn a lot in gambling you just have to know how to control yourself when you have so much money at hand and dont be greedy enough or else you will lose that money.