Existential crises are also a recent phenomenon, and involve a use of the word “existential” you won’t find in any dictionary. It … means “actually existing”. So an existential crisis is an actually existing one, which is the only kind of crisis you’re likely to come across.
Terry Eagleton quibbles with The perversion of the English language. I thought an existential crisis was one that threatened the existence of the thing affected, a situation that might kill, destroy or end (rather than merely damage) it.