I got big into the drug scene for a few years ago, and got out. For me, it was mainly experimentation, different ways of looking through the looking glass so to speak, and i actually resolved several problems that were causing me to become depressed while on X one night. I was 19 at the time and had recently had the time and disposible income to spend time with the "worldly" people in the first time in my life post JWs. I personally dont think of drugs as addictive, having tried almost all of them except for the stronger opiates. I look at it more as people not willing to deal with life, and instead take short cuts, easy way out instead of dealing with the issues. Its just another facet of the "blame game" everyone seems to love to play these days. I have also quit smoking 2 times, for atleast a year each.
I can see the appeal to the younger kids tho. Being a JW brings a lot of extra stress into your life. Not fitting into the social construct of normal life, extra time spend on meetings and meeting prep and studies and feild service. No drive to suceed b/c university is discouraged in most cases. Living a double life. Doubts that you can never bring up or question without being marked as a bad kid. The list goes on and on. If i was in an area with easy access to drugs when i was a teenager, i would have prbly used while i was still being raised in the "truth."