Privately owned things have been around as long as private property: ~20,000 years. Greed predates that quite a bit more - let's cut it off at the rise of modern humans: ~70,000 years.
Yet the "greatest reduction in both poverty and mortality" is a relatively recent phenomena happening during the rise of publicly accountable civic institutions. [1]
To then attribute this with something that did not lead to this process in the first 69,800 or so years is, in my opinion, pretty poor logic.
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[1] In fact, in Africa the greatest rise came after the decolonization post-ww2 and the establishment of states and representative governments. To say the predecessor extractive industries under colonialism weren't "capitalist" is also, quite incorrect.
I think this is a rather elementary (and Randian) view of capitalism. I don't know of any serious proponents of capitalism who claim that pure greed and self-interest is desirable. It is also a mistake to equate the existence of private property, or even the existence of limited free trade in primitive society with the effect of a society that is fundamentally capitalist in nature. And mercantilism (aka "crony capitalism") isn't capitalism either. Capitalism isn't the same thing as "some trade exists, that is somewhat free, for some people, sometimes".
