: 1) By the fact that capitalism is a system that humans use, it is natural to them.
Just because you use it doesnt mean it's natural to them, I'm using a computer if I introduced it to someone who'd never seen or heard of one before I'll betI could teach him to type but he'd probubly rather write.
: 2) A more natural system of exchange was codified by Machiavelli. That is, one gains through force (I take what you have) or fraud (I convince you to give it to me gratis). Trade is a much later development, and is a sign of more advanced cultures.
No not a sign of advanced cultures but advanced thieves my friend. If your going to rob someone blind if you do it in an obvious fashion then they'll oppose it, violently if they can, so it's easier if you can do it without them noticing. Or better still with their support.
: 3) The considerable efforts made to preserve free trade in the face of communism were primarily meant to stave off 'expropriation', i.e. communist looting. One might well ask, 'If the Jews truly did not agree with the Nazis, why didn't they make more of a fuss?' Or other such nonsense to that effect.
And the Communist looting was to stave off Capitalist "expropriation".