Speaking of the stereotype of 'mad genius', as opposed to the eccentric creative which this article is about, I would hypothesize that 'mad' is simply a mislabe

Speaking of the stereotype of 'mad genius', as opposed to the eccentric creative which this article is about, I would hypothesize that 'mad' is simply a mislabeling of the fact that those who are more intelligent are generally going to be less guided by social norms and more by their own logic and views. Being able to follow your own logic, without bounds, is something that is most people, for some reason, do not tend to do. Einstein is the best example of this. Relativity, and its implications, are intuitively insane and absurd. Yet his logic led him there and he invested an immense amount of effort and energy trying to prove it. And it turned out he was correct. In a parallel universe where the laws of physics are more sane, Einstein would have been labeled as insane for even imagining such an 'absurd' idea might be reality.