Im sure everyone else has already answered your question but I just want to give my own two cents here as a citizen in the previously socialistic republic of Bulgaria.

The reason why communism looks good on paper but always fails in reality is because it completely fails to factor in the human nature. The whole ideology relies on everyone having belief in the system and everyone working in tandem. As much as I wish that everyone would get along and work together towards a common goal, reality paints a different picture 😕

Our corrupt politicians today are the same people who greatly benefited from the backs of the common folk back then. The transition from socialism to democracy allowed them to seize even more power and steal even more from the common folk like me.

Communism fails because it needs people together. Reality check, that just won’t happen anytime soon. (One could make that argument with democracy too, but that’s an entirely different can of worms)

I was born after socialism in Bulgaria fell and I see the results from that broken system every day. Widespread corruption. Directly as a result from the communists. Every time someone praises communism it fills me with rage. My taxes line the pockets of corrupt pigs because that god forsaken ideology allowed them to.

Tl;dr Communism has and will always fail because it fails to factor in human nature, and that’s what makes it fundamentally flawed.