Governments are almost always the market for zero-days. Private security companies also buy them, but guess who their primary market is? Look at FinFisher's customer list.

There is nothing libertarian about the defense industry or their actors. Unless you mistake neo-liberalism as libertarianism as far too many people do.

> Your pro-government rant doesn't fit in this case because the government is one of the customers in the zero day market.

(Legitimate) governments generally are the only legitimate users of 0-days. Governments can legitimately and legally hack into your computer; nobody else can. Governments can legitimately and legally shoot you, but generally nobody else can.

One definition of government is that they have a monopoly on violence.

(I say "generally" above because there are exceptions, of course.)