Good subject, there isn't that much work done on the psychology of "libertarians".

They do tend to be more individualist in temperament than others, I think this is a key distinction. As far as a uniquely rooted characteristic it seems to be a general dislike of responsibility. Altruism, nationalism, and other collectivist modes of thinking require a certain subservience to a group or ideology which many libertarian minded folks try to distance themselves from. Hence many(at least started out like that) in the cryptosphere.