In a discussion with some supervisors the other day, I was reminded that if you want to determine why a person engages in negative or self-destructive behavior, consider what problem is solved by that behavior.
Most people do not willingly engage in behavior that is clearly harmful to themselves. Many have convinced themselves that the negative behavior is preferable to its absence and that while some behavior may be an undeniable "evil," it is a lesser evil. The perceived greater evil is usually not admitted or mentioned and so the lesser evil is appears to be the only problem in the room.
For example, a supervisor who is indecisive and overly analytical may do so out of fear of being promoted to a job in which he or she is far less competent and could do far more harm. What others see as that person's problem is really a solution.
The individual may find the will to correct the situation but only after finding a reason to do so.