How does this jive with stuff like http://www.pbs.org/wgbh/pages/frontline/meth/ which basically says meth is super addictive and the proof is the crime stats. Is it just that meth is different? Is it that the frontline piece is propaganda? Is it that meth might be super addictive but only to a small percentage of the population?
While the experiment shows isolation pushes rats, given no other options, to use drugs, it does not show that being social will save you from all drugs. Most addicts get into drugs through their peers. They do them with their peers until at some point they get addicted. Heck, the stereotype for some drugs is the drug house. It's full of people. Very social. But apparently that's not enough to save those people from their addiction.
I'm fully for legalization of drugs. Remove the crime. I also have plenty of friends who do various drugs and appear to be unaffected so I certainly see it's a myth for many that "one hit and you're hooked".