Gambling is just so addicting because of the fact that you can win money at the first place and because its a game and games can be highly addictive if you play them for a while and you find them enjoying.
I agree the fun and the profit that comes in playing gambling game is highly addicting. If you are winning, you keep on asking for more wins. While winning, there is this feeling of happiness that you will experience and get addicted to it. When the situation is reversed, you still keep chasing your losses and the idea of taking revenge take place.
That's addicting when you are both aiming for the fun and the profit, and based on my experience when I aim for both normally I easily lose my bets. Factors that would affect is that sometimes when I am too excited on the game I am vulnerable to chasing my bets, which in my normal plan it does not really include, but due to lack of self control I force to make it.