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.
Yes you can win here without much of a hard work and main addiction becomes after winning the few bets then even if some one looses he believes that he can win again,and gradually he becomes to come in loss and then try to gamble more to come in profit and in this game slowly he gets addicted.