Yes, it is the human element that derails these perfect systems. I think Darwin might enter into it somewhere, too.

As is the case with government, there probably is no such thing as an “optimal” economic system, only a best of the bad ones. Both Marxism and capitalism sound perfect in theory. Add in the human nature component, and either way you’ll end up with a wealth disparity between the rich and the poor that makes the Grand Canyon look like a hairline crack by comparison. In order to even out the disparity, more and stricter laws are needed, i.e., ever-growing government interference, which is precisely what the United States was designed to prevent from happening.

Not easy.