I think a possible answer JFT, is why does it work for everybody? I mean, why do people drink? I'd say beer is an acquired taste so, it wasn't our taste buds that kept us coming again and again. I think we're more similar with normal people in this regard than we realize.
Drinking removes social filters, we "relax" and say what we want (or sometimes what we regret.) It's a temporary euphoric, gives us an exagerrated view of ourselves and allows us to expand our social boundaries a bit. For many it gets us out of our head, out of our neurotic cycles, where we can "forget our problems." Zyprexa does not do this, nor any other psych med. And that's where the danger lies for those of us who crave it to an abnormal degree.
I don't think its too much of a head scrathcher because its been proven an exeptional escape route for humanity for millenia.
IF substance abuse is a real issue with us, then we must recognize that alcohol/drugs by nature are a temporary balm. THE greatest danger is that substance abuse is a progressive illness, and if you abuse, you will eventually get to a place where the drug no longer works for you. That's called "bottoming out" and its a pretty desperate place to be.
So, if you think you have a problem with drinking or drugs, there's a lot of help available out there. AA, NA, CA (cocaine) and MA (marijuana) are very helpful tools for many people, but not necessarily for all.
All I can say is that my life has completely turned around since I stopped using drugs and alcohol a year and a half ago. And for me there's a hell of a lot more to life than sitting in pub on a Friday night. I'm finally moving forward with my emotional and psychological development, finally beginning the healing process and recovering my life, and leaving DP/DR anxiety behind me for good.
The danger is if you abuse for the sake of self-medicating, your problem will stay exactly where it is. DP/DR anxiety grow to depend on the cycle of drug abuse and it becomes a snake-eating-its-tail kind of thing. Ouroborous. Very ancient metaphor for being stuck in life, doing the same thing every day and expecting different results.