Communism and capitalism are allies, and frankly two sides of the same coin. Marx repeatedly makes it clear in his communistic manifesto, that a society first needs to become capitalist in order to break down traditions and family, before it is ready for a communist revolution. He states that communists should side with capitalists against traditional society, and then get rid off the capitalists after that. Smart capitalist politicians switch coats and become loyal party functionaries when that happens, corporate leaders keep their nice jobs and report to the party instead of to the shareholders. Bankers remain untouchable in both systems.

Just the fact that people think the world is left/right, socialist/capitalist proves that these two allied ideologies have been extremely successful in the last century.