Exactly. I'm perfectly capable of taking or leaving cocaine. If I feel like doing a line if a friend pulls some out, I can do that, and never think about or crave it, years can go by between uses. Marijuana does fuck all enjoyable for me, Opiates though, i had a shoulder injury and the doctor gave me 20 5mg OxyContin's. I took one, once, and realized i absolutely need to never ever do any opiates ever in my life, best feeling I've ever had, seriously dangerous and I had a glimmer of how people get hooked on heroin.