The perfect victim, from the sociopath's point of view, is the person who is smart enough and capable enough to do him some good in the world and who is also fun to manipulate. How much fun is it to manipulate someone who is stupid and incompetent?
Sociopaths are not inhibited by the notion that it's wrong to be addicted, or wrong to buy illegal drugs. Also, drinking or taking drugs can be a lot of fun, and even if it's not, it can dull that painful boredom for a while. So can certain other things, like taking risks, and particularly if you take a risk-averse person and you can manipulate him or her into taking risks, that's really fun.
Another thing that's fun for sociopath is speed, literal speed, going very fast in your car. Not that everybody who goes fast in their car is a sociopath, by any means, but anything that gives you a rush will lessen your sense of boredom.
