They want to cultivate a feeling of control and/or superiority. You don't have to look too hard at your own problems if you preoccupy yourself with everyone else's. A lot of people also have a compulsion to make themselves "feel needed" by everyone. They tend to run through the motions of helping without actually doing much genuine helping. In fact, fixing your problems might mean you don't need them anymore, and they can't stand not feeling needed.