Years ago, when the dangers of smoking were less publicized, psychologists tested a group of smokers and then convincingly explained why it was in their best interest to quit smoking. The researchers later tested those who still smoked, and found they reported enjoying smoking more than they had before they were so aware of the dangers. This was apparently how their mind coped with knowing that they should give up smoking but finding that they couldn't quit.
It would seem that most people are under similar psychological pressures whenever they find themselves unable to change behavior that they know is not in their best interest.