Why the persistent demonization of commies?

I'm not sure most people who use it know exactly why other than it sounds good. Here's a little more history for you. Vietnam was fought to stop the spread of communism, that's the official version. Ten years later we had won nothing and had almost sixty thousand dead Americans. We never stopped communism. We do a thriving business with communist China, thriving for them, damaging to us and every American. The more we import from China, the more we only screw ourselves. In China the State is all powerful and our bankrolling their economy while they purchase our debt is one deadly combination. Watch and see in the future the buying of this country in bits and pieces by the Chinese government.