I guess what I'm getting at is that addiction is a complicated subject. Someone said only opiates and nicotine are addictive, but I disagree. Someone else (Maggie?) said maybe anything that makes you feel good can be addictive- I think that's closer to the truth.
It might have more to do with the addict than the substance. I suspect that for some addicts, if the substance they're addicted to didn't exist they'd be addicted to something else.