I'm sure they exist, but I've never met a Drug & Alcohol Counselor that hadn't been an addict. I guess you see what's at the bottom of the abyss and want to keep others from falling in.
Its weird, I've met a lot of social workers and many are just people good at helping other people. I've also met social workers that went into social work to save themselves. They were more screwed up then anyone they would likely meet in the course of their work. I think I've met the poster child for "why you shouldn't go into social work if...".