Earlier quoted context omitted.
Cuba's economy is closed to outsiders. Didn't make them prosperous. They have a state run bank, too. Didn't make them prosperous.
Communism doesn't have a great economic track record.
The DPRK seems to be a basket case, with regular crop failures (we are told), but its relationship with China ensures that it continues to survive.
Capitalism in countries like the USA seems to work for part of their population, but not all, there are large swathes of poverty and homelessness, and the disparity between the haves and have nots is enormous.
The whole point of an economic system, whether it be Capitalism, Socialism, or the more common middle ground (almost every country has struck a balance between the two, with Welfare states, public housing, public health, etc), is to ensure that resources are managed such that they provide for the population.
Capitalism is great at a micro level, people get to decide for themselves how to spend their time, what they want to eat/drink/wear/grow on their farms, and so forth.
But, it's absolutely horrendous at a state/macro level - can you imagine roading being multiple companies competing by putting half a dozen roads between yourself and your work? Emergency services have tried that model (Fire engines used to be owned by one insurance company, or another, and you would have a label on your home letting the crews know which insurance company you were insured by, so if the wrong fire crew showed up they would just watch as your home burnt down)
It's super easy to say "Capitalism has incentivised innovation" but the Soviets were ahead of the USA in several engineering fields, without capitalism (their incentive was competition with the USA)