People are self interested yes. Eliminating rent seeking behavior that is enabled by private property makes the social system harder to game for helping themselves at the cost societal good. Communists want to eliminate private property for this reason. Does this mean that all anti social behavior will be eliminated? No, but most crime is committed due to lack of economic opportunity. Politicians not doing what is in the interest of the people that elected them is often due to capitalist funded lobbying firms. Not having private property addresses those problems and other problems that are caused by those problems.