My coworker is like an ax.
In order to feel a sense of achievement, a feeling of accomplishment, he has to cut other people down. Sometimes he cuts people down branch by branch and other times he chops away at the base or stump of their tree. Tearing others down is all he seems to know how to do. It makes him feel good about himself. It provides him a sense or measure of self worth. It makes him smile and be full of glee. Just wicked.