One thing I’ll add that I haven’t seen mentioned is communisms relative weakness in the propaganda department. If you look at democracy as a bunch of competing interest groups i.e. parties trying to win the masses over to there side to win, then there main tool / weapon is information that will make the opposition look bad and your side look good, i.e. propaganda. Good propaganda requires intimate knowledge of people’s desires and a knowledge of how to shape those desires to the benefit of your program. Capitalism is very good at this due to competition forcing them to better understand there customer so they can sell them more. Capitalism creates great salesman which is fundamentally what you need to create good propaganda. You can see this expertise most plainly in advertising pushing the message that consumption is good, fulfilling and will make you happy.

This expertise combined with the large amount of resources capital can Marshall to push there message makes electoral politics extremely difficult for communism or any program that goes against consumption like environmentalism. Even if you completely eliminate capital and it’s control over media in one nation foreign actors will still come in using the same expertise and resources to try and bring back capitalism. So since communists can’t compete electorally with a free press they go towards autocracy to keep power.