If Libertarians believe themselves to be capitalists, and presumably they do as they believe in the supremacy of the free market, then yes, some capitalists or at least Libertarians who call themselves capitalists, do not understand the underlying requirements of capitalism, as you cannot have strong functional capitalism without property rights and the rule of law that government provisions. But the crucial point beyond that, which I suspect you are missing is that in a world where people are organised into competing groups, under governments, - nation states are competing for resources - raw materials, labour, capital and markets - and it is the nation state with its diplomats and the military standing behind the diplomats that strongly influence the availability to raw materials, labour, capital and markets. 'Free' markets do not exist in isolation from the laws and monopoly over the use of force that nation states claim. Good government is essential to enable strong economic growth and wealth creation. Government is a crucial driving factor in the wealth of nations. In denying the crucial role of government Libertarians commit economic treason by seeking to undermine the fundamental requirements of a strong economy.