In my first Creativity post, I was referring to creativity addiction. It seems like many artists can easily have this.
But something that just has to be said when talking about addiction is that everything that can possibly be fun can be addicting. Gambling, shopping, sex, video games, eating, making people laugh, clockmaking, stamp collecting, etc.
All these things alter your brain chemicals; drugs just happen to do so directly.
Being in an altered state from drugs makes people look dumb sometimes. That's why those anti-drug commercials with the fried egg were so popular. But (most) drugs don't "fry your brain", they just alter it temporarily. If people got the "runner's high" more often while jogging, there would probably be a movement trying to ban marathons.
Life is pretty much just one big mind alteration, and any part of it can be addictive. It's too bad people are focusing on drugs now instead of filling prisons with fat people. Possession of more than 12 donuts should get you 1-5 years. Sorry officer, you're going to jail.