Sure - there's definitely some of that.

There may also be some distrusting "Why is my manager encouraging me to leave? I'd better dig myself in and make sure I don't fuck anything up" thoughts (although I'd like to think I'm not thought of as "that guy").

But I also see cases that are closer to a reverse Dunning Kruger effect, people who just don't realise (or admit to themselves) how good they are compared to their peers. (Sometimes at an astonishing penalty to their earnings...)