That's what some people are asking in the face of the renewed revelation, in reviewing the life of Nelson Mandela, that he, too, was reviled as a Communist for opposing a segregating regime in his home country. Since he was obviously a fighter for freedom and former antagonists now find it necessary to re-write history, it seems useful to consider what about Communism makes it seem such a persistent threat.
The answer, I think, lies in the fact that communal use or ownership of real assets vitiates the nominal importance of private ownership. If everyone shares, then there is no advantage to ownership and if owning private property is not important, then there is nothing whose threatened removal can be used to coerce compliance.
For a long time, I've been referring to private property and home ownership, in particular, as a sop -- to compensate people for the violation/disrespect of their human rights. Perhaps calling it a snare is more accurate. People are persuaded that owning things, including other people (children, wives, slaves), is such a good that the surrender of themselves is worth it.
Private property is a snare. It is also a continuing deception because the suggestion that an individual can do with his/her property whatever he wants is false. It's not true about children; it's not true about wives and it's not true about real estate.
Why does the U.S. have to persist in a culture of deception? Those are the wages of its original sin, of having been conceived as a state based on legal human slavery.
What is profit but a surplus which can be requisitioned without affecting ownership of the whole? Profits are the wages of ownership, which isn't a boon to begin with. So, when the deception that lies at the basis of ownership is revealed, the system is bound to collapse because people will surrender ownership quite voluntarily.
Marx, in writing about capital, made the mistake of focusing on the object (that which is owned), rather than the function or process of ownership. Once the process is understood, it will be voluntarily given up as coercive. Mobile creatures do not perceive comfort in being tied to the land.