Why is Ron Paul a Republican...

... and not a Democrat?

No. I didn't say, "...and not an independent?" I know why Ron Paul is a Republican. It all comes down to practicality. You get elected in this country by being a member of one of the two parties. That is not the question though.

Looking beyond Ron Paul, more generally, the questions is why are libertarians often seen in the main stream as conservatives and not liberals? A libertarian is some one who believes in self-reliance and freedom to do what one chooses so long as it doesn't harm others. They often find it convenient to label themselves fiscally conservative and socially liberal. But if so, why are they typically labeled as "wacky conservatives" and not "wacky liberals"? I have three partial theories that may sum up to explain the phenomena...

1. Libertarians are just conservatives that don't let religious and nationalistic beliefs sway them into enforcing their morality on others.
2. Liberals have an urge to "do something" to fix our unfair world. They can't just sit idly by while people are homeless or without health care... "if we just spend a little more, it will help so much!" A libertarian believes that the best way to help more people fiscally is not to throw more money and government at the problem but to take more harmful government out of the equation. Liberals see libertarians sitting "idly by" and take that to mean they don't care about the poor, which fits in nicely with the stereotype of the greedy, rich conservative.
3. I should note that the libertarian is often more passionate about personal freedoms than the liberal, so why do liberals overlook this passion? Perhaps liberals, contrary to popular belief, do care more about "loyalty to the cause" than conservatives. You are either with the program or against it... everything is an ideal from welfare to free speech, we cannot sacrifice any of it! Whereas conservatives can tolerate some quirks. Heck conservatives probably would rather that the government were not as harsh on social issues such as drug prohibition and personal privacy, because that would let people make decisions for themselves, which in religion, is the only way to be righteous (you must be able to choose), but their overwhelming urge is to have safe neighborhoods and dead terrorists, ideals be damned.