Every employee rises to incompetent levels

Laurence J. Peter first formulated and named the phenomenon in 1969, in a satirical book "The Peter Principle," where he stated that "In a hierarchy every employee tends to rise to his level of incompetence ... in time every post tends to be occupied by an employee who is incompetent to carry out its duties ... Work is accomplished by those employees who have not yet reached their level of incompetence." 

• You will see that in every hierarchy the cream rises until it sours.
• An employee does well. He’s rewarded with a promotion. He does well in that job, and is promoted again. This continues until the point he is no longer performing at a level deserving of a promotion, which leaves him at a level where he is incompetent.
• Being incompetent, they do not qualify to be promoted again, and so remain stuck at that final level for the rest of their career. 
• What’s true in general is often not true in particular. 
• A company that relies too heavily on sales as a criterion for promotion pays twice for the mistake.
• When good worker is promoted as supervisor and if he turns out incompetent then the firm lost a good worker and is saddled with a bad supervisor.
• One of the greatest pieces of self-awareness is the knowledge that management, whatever its perks, might not be worth the burdens it will impose on you.
• If a top-selling colleague from your team just became your new boss, it might be time to move on.
• Certain groups of managers – notably women and minorities — who weren’t promoted despite their competence and so didn’t get the chance to reach their level of incompetence. 
• The traits of good followers are nearly the same as the traits of good leaders. They “manage themselves well; are committed to the organization and to a purpose, principle, or person outside themselves; build their competence and focus their efforts for maximum impact; and are courageous, honest, and credible.”  If everyone were like that, the Peter Principle would probably never have been written.
• Percussive sublimation, in turn, is related to the Dilbert principle, which maintains that the real purpose of the hierarchy is to provide managerial roles that will minimize the ability of those employees to interfere with the actual work being accomplished by more productive staff members.