People often backbite due to low self-esteem, jealousy, or a desire to pull others down to their level.

The Impact of Backbiting: A Guide to Recognizing and Reducing Destructive Gossip

Insulting an "enemy" after a confrontation can temporarily restore self-esteem.

Individuals may join in to gain acceptance from a group. The Consequences

Sharing a grievance with a confidant can build a sense of unity, as the "enemy of my enemy" becomes a friend.