Socialism has never worked because dictators and authoritarians take control. It has weak protections against authoritarians, or authoritarians use socialism as a carrot to entice the masses and never delivering on their promise. Same with communism.

Fidel pisses me off so much. He achieved amazing things in the name of prosperity for all the people, then went and killed or imprisoned political opponents and LGBT.

However the continued sanctions against Cuba are blatantly in place to make sure socialism doesn't "work".

Are you attributing reduced infant mortality rate to capitalism? Because then you can look at the same graph for Cuba and also attribute their reduced infant mortality rate to socialism

With US history of interfering in Latin America countries I'm sure there's a link to the CIA, USAID, and the state of those countries economies and governments.