Slavery was wrong and so is capitalism. It is wrong because it stands against human freedom and creativity. I support a particular form of communism called communist- anarchism. State socialist experiments have not worked in the context of the capitalist world-system. But just because my car runs out of gas 10 miles to New York doesn't mean that I should throw my hands up in the air and pledge never to go to New York.
Communism is a better world.
Human beings create their worlds. And so we should set about creating a better one. Capitalism is exploitation. It is wage-slavery. It creates poverty and suffering.