Popper vs. Libertarianism
Popper thinks that Marx's theory of the state is a fatal flaw, and I certainly agree, but he argues that Marx came by it honestly:
For Marx lived, especially in his younger years, in a period of the most shameless and cruel exploitation. And this shameless exploitation was cynically defended by hypocritical apologists who appealed to the principle of human freedom, to the right of man to determinate his own fate, and to enter freely into any contract he considers favourable to his interests.
Popper, Karl R.. The Open Society and Its Enemies (Princeton Classics) . Princeton University Press. Kindle Edition.
Of course our libertarian friends continue to say the same things, mostly, I think because they don't want the government interfering with their freedom to deny freedom to everyone else. The fact that they largely cannot carry out their program in Europe is a big point against the Marxist theory of the state. Of course the US is a somewhat different story, where the plutocrats have more success in enacting their kleptocratic dreams.