Everything you do is an addiction. You eat because your stomache nags your brain to eat until you finaly do eat to get the nice chemical relief of being full. Same goes for sleeping, drinking, sex and prety much anything you do. Weed is defirent imho I think we (or at least I) smoke weed because an altered reality is much more fun/interesting then one that I live in everyday and it must release some kind of hormone because I always feal happy when I'm high.

Hormons and chemicals control most peoples lives or at least have a major effect on it.