I find the extreme sensitivity displayed by libertarians toward criticism of the Koch brothers is really strange. Here's a typical example, from David Bernstein:

The ongoing twenty minutes of hate against the billionaire libertarian Koch brothers for being, well, billionaire libertarians is yet another nail in the already well-sealed coffin of “liberaltarianism”–the attempt of some libertarians to ally with the progressive left.
The underlying premise of liberaltarianism was that libertarians could emphasize their policy positions that appeal to liberals but not conservatives–drug legalization, hostility to war and military spending, support for civil liberties and for gay marriage–while liberals, chastened by the Bush years, would tone down their support for big government in other areas.
The Kochs would appear to be the perfect liberaltarians–they support gay marriage, drug legalization, opposed the Iraq War, want to substantially cut military spending, and gave $20 million to the ACLU to oppose the Patriot Act (compared to a relatively piddling $43,000 to Scott Walker’s election campaign).

The comparison to 1984 lends this complaint an especially melodramatic touch -- the point of the two-minute hate was that it targeted powerless or fictitious villains. I'm pretty sure that Emmanuel Goldstein was not supposed to have been actually exerting enormous influence over the political system in Oceania.

And the notion that the Kochs are "perfect liberaltarians," of course, completely misses the point of liberaltarianism, which was to emphasize social issues and foreign policy over economics, and to define economics as evidence based and less hostile to redistribution and the possibility of market failure. Koch-brand libertarianism is obviously the precise opposite of each of those characteristics.

And while I certainly can't speak for the liberaltarians, I suspect liberal criticism of the Kochs is unlikely to send them back to Koch-funded right-aligned libertarian organizations, given that those organizations very recently purged the liberaltarians.

But leave all that aside. Why do libertarians find it so offensive that people would criticize the Kochs? They exert a great deal of influence over the political system. Nobody is challenging their right to do so, but the fact of their involvement makes them natural subjects for criticism. Conservatives (and libertarians) enjoy criticizing and ridiculing figures such as Al Gore, Dan Rather and Paul Krugman, who influence public opinion as well, and whose pecuniary interest in doing so is, at best, much less obvious than the Kochs'.

The hypersensitivity about this honestly baffles me. Some of it has to do with the discomfort libertarians, who enjoy their self-image as scrappy outsiders, feel at association with powerful moguls. Some of it may result from the fact that it's unusual for a libertarian to assume such a high-profile role in American politics, and so libertarians may not blink at criticism of a George Soros or an Adolph Coors but suddenly find their hearts bleeding at the sight of libertarian moguls facing actual public scrutiny. In any case, the sheer self-pity on behalf of these extremely wealthy, powerful individuals is quite a spectacle.