Trying to keep my reasoning succinct in order to avoid writing a wall of text:
The soviets were geographically blocked from this being an option
Similarly for Vietnam for different reasons
Cuba doesn’t have the option of dedicating the requisite amount resources(and has the misfortune of being an island next to the most powerful current naval power)
China has the geography to become a great naval power. Sure, it doesn’t have both coasts. It has land connections that led to the Silk Road being a thing on the other, possibly a greater advantage.
They are building up militarily, and seem to be advancing commercial maritime pursuits on this well.
Thoughts?
The USSR could never compete with the combined NATO surface fleets. (USN+RN alone was massive) Simply not enough resources could be possibly dedicated to it, the Atlantic powers had been building ships for centuries. Submarines were the right call for the USSR, there it was possible to achieve an asymmetric advantage.
This is what Khrushchev (who I admit was usually a hare-brained oaf, but he made sense here) said about it: "The Americans had a mighty carrier fleet - no one could deny that. I'll admit I felt the nagging desire to have some in our own navy, but we couldn't afford to build them. They were simply beyond our means. Besides, with a strong submarine force, we felt able to sink the American carriers if it came to war"
from a purely nerd perspective khrushchev cancelling all those projects was a tragedy but the reality was that most of the projected stalin era surface fleet was a pipe dream. that said, the modern surface ships the soviet navy actually completed right after the war were all very solid designs that were more or less on par with their peers.