[I]nfluential mistakes create something neither anticipated nor inevitable, while right ideas are somewhat inevitable. Thus good ideas are not so dependent on “great men” because there are lots of smart people and they eventually find the truth (witness the simultaneous discovery of things like evolution by Wallace and Darwin, calculus by Newton and Leibniz, or marginal analysis in economics by Menger, Jevons, and Walras). Bad ideas, in contrast, are infinite in number, and require a special magnetism and impenetrable self-assurance by their champions in order to become influential. Freud is a perfect example, a charlatan who befuddled two generations via his implacable self-esteem. Marx was similar, and Ayn Rand was cut from the same cloth but fortunately her radical ideas against empiricism never had as deleteriously wide an impact as Marx or Freud.
The pièce de résistance:
So for an individual to have great impact, it is probably in some wrong-headed idea about something not obviously falsifiable.
(Not just idea people; nearly anyone remembered as “the Great” was an abominable person.)
That’s most of the post, but read it again, it’ll be fun: The Most Influential Individuals are Generally Bad.