Communism is often misunderstood as a political system. It is more than that. It is a way of life. An outlook towards reality. In this sense it is more of a religion than anything else.
While it is true that it has prescriptions on how society has organized, it also has prescriptions on how one should live life, and think about everything. This is why every communist country ends up having similar histories. From Somalia to the USSR to North Korea, it is the same story over and over again. Why would that be?
People create history. But people are driven by philosophies. Even nihilists hold nihilism dear. Buddhists are attached to Buddhism. People who say it is better to not be driven by an ideology have an ideology about not having ideologies. This drives them to act on whim and expediency of the moment, which happens to be their philosophy. As Alan Greenspan confessed: it is impossible to exist without an ideology i.e. a system of ideas. So people driven by philosophies drive history. And blaming people for adhering to a system of ideas is hypocrisy. The modern ideology is about blaming people with ideologies.
Communism is a philosophy. On every question, there is a communist answer. And I mean every question, even basic questions like "Is there anything?" or "Do you possess a faculty for perceiving that which is?". Starting from such fundamental opinions it builds itself up, to a philosophy of science all the way to morality and from there into politics. Not all of it began with the invention of the word Communism. A lot of the ideas Communism uses has existed as a part of human thought for millenia. Since Plato and before him. Communism merely organizes them into a hierarchy and names them.
Tyrants of the past believed, ideas could be destroyed by destroying people with such ideas. This is wrong. Ideas are bulletproof, as V said. Ideas can only be destroyed with better ideas. And by being better ideas, they ought to correspond with reality more strongly while remaining consistent.
In this sense, Communism is not a better idea, than ideas that preceded it. It fails to correspond with reality in many ways, and its practitioners exhibit inconsistent thinking and often openly flaunt the futility of being consistent & logical. (e.g. Slavoj Žižek).
There are better ideas. And they will prevail over time.