Question: Bullying is a major issue at my child's school. Can you help me understand why bullies bully?
Answer: There are different perspectives on bullying, but one of the most common theories suggests that bullies primarily want to gain status among their peers. Two needs underlie this drive for status: a need for popularity and a need for domination. Any given bully may experience one of these needs more than the other (for example, a particular bully may mainly want to become popular), but it appears that all bullies have both needs to at least some extent.
Understanding why bullies bully can help us understand how bullies pick their victims. For instance, bullies who primarily desire popularity seek out victims who have been rejected by their peers. If the bully instead picked a victim who was socially well-connected, it's unlikely that the bully would become popular by attacking that person.
Bullies who primarily desire domination look for victims who are vulnerable and unable to defend themselves. In other words, they seek out victims who can be dominated easily and who, ideally, won't tell anyone.
Given that all bullies have both a need for domination and a need for popularity to at least some extent, the "perfect victim" combines both attributes: someone who is vulnerable and socially rejected. That said, though, not all victims fit this picture, and not all bullies bully for the exact same reasons.
Veenstra, Rene, Lindenberg, Siegwart, Zijlstra, Bonne, De Winter, Andrea, Verhulst, Frank, and Ormel, Johan. The dyadic nature of bullying and victimization: Testing a dual-perspective theory. 2007. Child Development. 78,6: 1843-1854.