i agree that it's more about the state of mind someone is in when they start smoking weed, than weed actually having some kind of property that sends you off the deep end.
the first shit i did, not counting caffein and things of the like, were my perscriptions.
i remember taking ambien, thinking it wasnt working, taking more, becoming fucked up enough on it that i realised what it was doing, and than eating the rest of the script over the next few days. i was 13, and i couldnt believe that something i got from the doctor could produce such a feeling as i'd never had, to actually step outside what i normally thought and act all loopy until i passed out.
what brings us to other drugs, is the fact that we did any in the first place. it's crammed down your throat from the time your a kid, that they are wrong, and once you've crossed that threshold of rebellion, a revolution takes place in your mind that you'd rather not integrate back into the common opinion without seing for yourself... i think thats why most people are led to post in a forrum like this anyway.
i love the insight and level of personal growth, and spiritual development psychedelics have given me, but that wasnt my attitude getting into it. i was looking for something that fucked me up, and it turned my world upside down... but thats another story, for another thread.