Peter Principle

A workplace-psychology phenomenon whereby it’s extremely difficult to de-promote someone once they been granted a promotion – no matter how badly suited they are for their new role.

Coined by Kevin Kelly:

a person in an organization will be promoted to the level of their incompetence. At which point their past achievements will prevent them from being fired, but their incompetence at this new level will prevent them from being promoted again, so they stagnate in their incompetence.