Per Brian Leiter, Robert Hockett amusingly speculates that Ayn Rand's success is due to "the way in which she afforded a sort of vicarious self-flattery to narcissistic imbeciles."
True enough, but it also cuts against Brian's point that Ayn Rand has nothing significant in common with Nietzsche! How many self-consciously serious types are walking around with copies of Zarathustra in their hands believing that they just might be the Übermensch? Alas, if only they knew that the highest, Promethean greatness consists in inventing a new type of motor.
Oh, and read all of Brian's post.
