Mainly the brutal reality that people would rather burn different ideas at the stake than give them a try.

The crux of Libertarianism is nothing more than "the ethic of reciprocity" (http://en.wikipedia.org/wiki/The_Golden_Rule) - what's novel is the idea that we should hold governments to the same standards as individuals when it comes to stealing, enslaving, and murdering.

Similar view on Bitcoin as well. Simple idea - no middle-men meddling in your monetary exchanges. When it comes to that, Bitcoin works great "in reality".

Seems pathetic to take the position that these ideals shouldn't be persued "in reality". From where I stand, only a sociopath would stand against them.