Tha greediness is the main reason of addiction. If people already know how to be contented then they would stop if they hit there target already. Gambling is a mind game that requires intelligence a little luck, emotions must be set aside while playing to have a sound decision making in order to stay in the game.
Well all of what you said is probably right and that is really is gambling it really requires intelligence and luck and emotions are not really required in this kind of game because it can cause you a lot, because probability that may cause this losing is your emotional state if you feel frustrated and angry you will decide in going all out then the timing is not right that will probably a worst case in your career in gambling.