It is interesting, isn't it? You might expect there to be a 'general factor of criminality/antisociality/violence' akin to how we find a general factor of intelligence in psychological things, but as far as I can tell, drug use or sales seems to be largely orthogonal to other kinds of crimes - most of the DNM users will never buy credit card dumps and rip off retailers (carding is disliked by a lot of DNM users, although not enough to totally ostracize it like CP), most DNM users will never download CP, most DNM users will never beat or rape someone, etc. I have no issue buying and using illegal drugs, so I'm a criminal, but I'm not the same kind of criminal as, say, the Vallejo kidnappers (which BTW if you haven't read the complaint, it's an amazing read if you're into true-crime stories: http://www1.icsi.berkeley.edu/~nweaver/vallejo.pdf ).

This probably has a lot to do with why the War on Drugs has been such a failure and why legalizing does not seem to unleash crime waves.