The ease with which people can possess astonishingly contradictory qualities is one of the mysteries of human nature

Be a Jerk: The Worst Business Lesson From the Steve Jobs Biography by Tom McNichol.

The ease with which people can possess astonishingly contradictory qualities is one of the mysteries of human nature; indeed, it's one of the things that separates humans from, say, an Apple computer. Every one of the components that makes up an iPad is essential to the work it produces. Remove one part and the machine no longer performs its job, and not even the Genius Bar can fix it. But humans are full of qualities that are in no way integral to their functioning in the world. Some aspects of personality have little or no bearing on whether a person performs well, and not a few people succeed in spite of their darker qualities. You can be a genius and an asshole, but the two aren't necessarily causally linked.