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Communism requires a leadership which will uphold the laws of communism and will not become manipulative or corrupt. Also the people must share the same crisis to determine that communism is the best way forward. This is very challenging to find.
Historical communist leaders have strayed from communist ideology and have abused their power and changed the political system of the society to a totalitarianism-style model.
Communism is useful because there is no class system - everyone is valued equally. Also, the wealth is distributed equally so everyone has the same level of financial happiness. This is the key to preventing conflict for resources.
It stops couch potatoes from being created as everyone has to work.