A grandiose windbag who bullshits for a fee. They can't do anything useful, so they enter teaching, but they find out they can't teach very well so they try to teach teachers, but the teacher they teach think they are tossers, so they become academic consultants.

Adj. Something that is expected to have a long lifespan by virtue of having existed for a long time, based on the lindy effect, named for the New York restaurant Lindy's, coined by Albert Goldman and popularized by Nassim Taleb.