It appears the Vietnamese, like the Chinese and Russians, have found Communism is not all it’s cracked up to be.
They also had a really good example early on after the war of how when taken to its natural extremes communism is quite lethal to its citizens - remember that the Vietnamese were the ones that had to stop the Khmer Rouge in Cambodia to put an end to the Cambodian Genocide. They got a really good look at what can happen and decided they had a couple million reasons that they didn’t want to go down that path.