Regardless of what level of success they may have achieved in their chosen field of work or study or what external proof they may have of their competence, those with the syndrome remain convinced internally they do not deserve the success they have achieved and are actually frauds. Proof of success is dismissed as luck, timing, or as a result of deceiving others into thinking they were more intelligent and competent than they believe themselves to be.
--Impostor syndrome via Wikipedia via Hacker News Comment
via Dustin Curtis's blog post about The Rich and Powerful