I think you're missing a large component of libertarians: People who want to be outsiders or contrarians. If you watch the documentary The Most Hated Family in America about the Westboro clan, you'll find that one of the converts proudly declares that he foolishly used to believe libertarianism, until he found the teachings of Fred Phelps. He's now in one of the most outside groups in American culture. I think this is a big draw for some people, and it attracts them to cults, conspiracy theories, and unpopular political/philisophical theories.

I don't know what percentage of libertarians they make up, but I'm sure they exist. 30% wouldn't surprise me.