I think there is a combination. Some people are driven by success and will do anything to get there. That can meet locking out every aspect of their personal life to get there. I also think some people are not happy in their personal lives and will stay in the office to avoid any issues at home.
I think addictions tend to be expressions of something deeper within the addict. In that sense both avoidance and addiction go hand in hand.
I don't think it's an either/or kind of thing. Addiction in general is often a way to escape unpleasant part of life. Some people do it by getting high on drugs, and others by focusing on work to the exclusion of everything else. Working becomes a compulsion that they just can't resist. Being successful in their career gives them a kind of high.
I think you raise a good point, though--there are probably a lot of people who spend long hours at work just because they don't want to be somewhere else. Instead of an intense drive to succeed at their career, they just hang out at the office because they don't want to go home.
Click Here to search for a treatment center in your state that is right for you.