Libertarianism shares one thing with communism in that they are both utopian dreams not realizable in a real world.
Communism has the "advantage" that it can be twisted into a tyrannical dictatorship that is at least good for those that end up at the top ... so long as they stay at the top.
So I guess libertarianism is silly in that if it ever did get established for a short bit of time, those that put it in place would be just as likely as everyone else to get screwed over once the government started grabbing back power.
The really silly thing about libertarianism is that anyone with a sufficient amount of intellect and stick-to--it-iveness (and a modicum of luck) could live a libertarian-like lifestyle so long as they didn't try and impose it on anyone else. If you are wealthy and discrete you can get away with a heckuva lot for a heckuva long time.
You don't have to be wealthy. I wouldn't call my son in law a libertarian; but he is quite poor, but he manages just fine as he buys, fixes and sells cars for a living. He's never paid any income tax as he is off the grid. He owns some 8-10 cars at a time but they are open titles and so he pays no sales tax or registration fees. He'll buy a junker for a few hundred bucks, fix it, sell it, and clear a thousand or so.
He and my daughter are quite happy, so I'm happy for them. He's a poor "John Galt".