An important element of the Peter Principle (the book) is that if you know that you have reached your upper competence limit in the organisation, you might have to take measures to prevent further promotion. Or in some cases (incompetence level achieved!) you might even have to engineer a way to drop back to your old job.

The book mentions the case of the guy who "accidentally" parked his car in the big boss's spot once a month or so, to forestall promotion.