It's never real communism until they're the ones in charge, and when things still go wrong it won't be their fault - the evil capitalists are to blame! They believe that communism will be a peaceful transition that doesn't create a power vacuum and allow homicidal maniacs to take control. But the very nature of a changing government is unstable and creates a power vacuum, and with the transitory period between socialism and communism gives absolute power to the state. Of course, the state will never give up it's power because no one takes power with the purpose of giving it away, so communism won't be obtained and once again it'll be "not real communism".