When you come back there again to restore your lost money then you become very addicted. So if you consider gambling as a means of earning money then you are a real gambler, you find a way to control yourself.
This has being a constant reminder to all gamblers to gamble without intentions of earning money but basically even without getting anything from it people get hooked along the line. But then i quote you wrong saying earning money from gambling makes you a real gambler. Absolutely it doesn't the fact that you gamble and know when to stop makes you a real gambler.
If the definition of gambler comes from the money they earn, there will not be a lot of real gamblers out there. Everyone has different kinds of definition of a real gambler. Even those who have never gambled have their own definition of what a gambler is. It is hard for everyone to come into only one conclusion. The best we can do is to take the common characteristics and we can define what a gambler is. Probably anyone who take risks is a gambler.