It's that thing a lot of people seem to achieve when they get successful either though luck or talent, and start acting like, or maybe actually believing, they are the smartest person in whatever room they walk into. Unfortunately it hovers on that line between confidence and overconfidence, and far to many trip over that line, especially when they start surrounding themselves with people who have no choice but to feed that expectation. They start to push against the line, justifying their missteps until they can't even see them in any sort of perspective anymore. It's when any criticism is considered a personal affront, when questions are considered an attack and someone disagreeing with them isn't disagreeing, they're wrong.