This person is highly idiosyncratic/unpredictable and has multi-day bouts of mania with extreme energy, before flipping into a depressed/alcoholic state where he's a no-show for a week. Probably he applied during a manic phase.

Needless to say he has an IQ of probably 140+ so he can impress people especially during the interview stage with his sheer intelligence. He can also build things fast. Everyone who works with him acknowledges the skill but finds him too destructive personality wise and it usually results in termination within 6 months. He's switched to remote consulting recently which is a better personality fit.