Alcohol isn't a bad addiction. Of course, if you go overboard by becoming an alcoholic, then yeah, it's bad. Otherwise, it's supposed to make you happy, it's supposed to ease your well being.
Gambling isn't bad, you just need to have the right amount of money to lose (ahem, burn), and you have to know how to play the game, and understand that it's either pure luck, or you can calculate your next move. There are two movies that reflect this. ("21" and "The Gambler")
In the Gambler, a teacher drowns himself into debt, only to say "fuck you" to the debt collector because that's the point of it all. You gotta watch "The Gambler," because the guy who collects the debt gave one of the best acting "quotes" you can find when it comes to gambling. I don't remember what he said, but it was fucking brilliant. The actor doing the scene should've gotten an award for that. Brilliant.
Now, drugs is a whole 'nother ballgame. It's as advertised. Once you drown yourself into drugs, there's no going back. That is, until or if you plan to quit. Otherwise, once you drown yourself into that abyss, there's no going back.