Please send that note to Fidel Castro.
Cuba does not exist without other people's money. Funds and goods pour into that island nation from all over the world.
No rule is absolute. There are exceptions to every rule and frequently those exceptions only serve to prove the rule. I put Cuba in this category. People like to cite the ‘success’ of Cuba despite the decades-long embargo against them and use their continued existence as proof that embargoes don't work. BS. Embargoes are like capitalism and abstinence, they work every time they're tried. For most of Cuba's existence it was the benefactor of the largess of the USSR. Even with the collapse of that system there is no meaningful embargo of Cuba.
I understand your point, and it's well taken. I just don't think Castro is a fair example of how socialism can work carry its own water. If America had ever set its mind to the task Cuba would have been liberated from Castro and his thugs any number of times over the decades.
You are using a different measure of success versus failure than I would expect most conservatives would use. Mere existence isn’t success, as we shall all find out shortly.