Best social experiment in the world proved communism is a failure and continues to do so today.
North Korea versus South Korea.
Prove me wrong without resorting to trying to blame America for not trading with a nation who declared they wanted the USA wiped off the face of the planet and sided with its most die hard enemies after the US tried to liberate it after WW2.
You can't do it.
North Korea had it all. It had open trade with the USSR and China. It was given more financial aid from both those entities than you can possibly imagine. Long before the USSR broke up and stopped giving it cash, and long long long before China gave up on it (China still gives it food and money aid hand over fist year over year in fact) the North Korean economy, structured on Juche ideology founded on Marxist and Maoist principles, had ground to a halt.
The worst part is that North Korea was economically, educationally and militarily stronger than South Korea but within 15 years those roles had reversed and now North Korea is hell on Earth, and South Korea exports this to the world every day
Now, the typical response will be to blame America or the West for North Korea's failings. This is a false argument, North Korea declared war on the United States, regularly calls for its destruction, allied itself with our greatest enemies post WW2 and basically brought every single thing that's happened to it since entirely upon itself. We had no responsibility to make sure North Korea was successful, yet here we are, 50 years later, still sending them food aid and even arming them with nukes, anything to make them just stop being idiots and start fixing their nation.
Also, Mikhail, the argument for Catalonia is a case of special pleading fallacy. You can't point to an ocean of failed experiments and say "This one experiment, which also failed, but which failed because of a confounding factor, would have certainly been the one case to succeed where all others failed, if only it hadn't been confounded mis process!" That's some goddamn Lumie levels of special pleading.
Now, was it the Yugoslavs or the Czechs that had an independent Communist state run by a benevolent dictator, Tito Ortiz? Or are the same thing in this time period? I can't even remember. Fucking balkanization. Anyway. That's a better example of a semi successful Communist state.
Still a pretty shitty one, though, because that communist state was overthrown in 1989, so it failed too. Just on a much longer time frame. But really, most examples are going to suck when the people who think you're wrong can point to the USSR, Mao, Cambodia, North Korea, Cuba and Venezuela all as examples of the outright devastation that die hard communist ideology causes. Its kinda like being a Nazi. Yeah you can point to how great Hitler ran the country economically before the war, and claim that justifies National Socialism, but then the people who disagree are just going to point to the concentration camps, the total destruction of Europe, the racist ideologies, etc. and say "Yeah, you know. Running a decent economy for a few years doesn't really make up for all that."
Mixed economies are the real success story, if any experiment on economics can be see in this light.
Mixed economies that embrace capitalism and embrace socialism as necessary based on events as they transpire are where all the successes are, really. Pure laissez faire capitalism doesn't work any better than Communism or Fascism.
Worse, in many cases.