There is a reason young people and thoughtful people find Ron Paul interesting.
Paul is not a rabid Repuglican partisan ... he is running to promote a particular political philosophy.
His version of libertarianism skews to the right, conservative side. But there is leftist libertarianism, it is akin to anarchism, the libertarian socialism of the Chomsky variety, etc.
There are places where right and left libertarianism coincide ... and that explains the disdain of concentrated power, empire building, militarism, so on and so forth.
I think that those who are party tribalists in both parties (people who just want their side to win, regardless of principles or issues) find a candidate like Paul a threat. And you see it in the Repuglican Party right now -- party establishment types hate Ron Paul because he really exposes their hypocrisy and double standards.
No doubt Ron Paul is a flawed presidential candidate, but I suspect that that is not as important to him and his followers as advancing their philosophy.