Addictions is hard to stop that's why one must try to prevent it so that they won't become addicted to anything. However just been saying this before now that addiction doesn't start just in a day, the gambler develops it gradually and that's how it becomes use to him or her. IMO, gambling addiction is the worst of all the things you have mentioned because some people can do anything for them to gamble, they can sell their properties or use people's money to fuel their gambling addiction. But one who's addicted to alcohol and drug might have friends that's also addicted so if this person do not have money to buy the hard drugs/alcohol the next person might have. Although the both are not something one should become addicted to because they are not good.