Yeah but that's why you go and make a small society in a largely unoccupied area and make it self-sufficient.
That's why Hippie communes work so well. In large populations communism is a baaaad idea, people are told what to do, they have no incentive to work, which means efficiency and quality is down. And your house is owned by the state, which means no individual freedom, you don't get any special rewards or promotions if you work harder then the guy next to you.