But my "Ashcan of History" optimism stems from this: When people see the natural conclusion of Communism, its death camps, its slavery, its dehumanization, its nihilism, which we ALL have seen this past century, people generally are wise enough to think about turning away from it.
This is an advantage we have now with a somewhat better informed populace and a religious revival emerging.

Yes, exactly. You've got it. Communism is just a package for human failings, like sloth and envy and the others you listed, made to look like an enlightened system of government. It fools only the stupid and those ignorant of history.
In no other system of thought are "useful idiots" an integral — perhaps even essential — component.