Breh not sure what your talking about capitalism has built China and Vietnam. They are ruled by a communism ideology but practice a capitalists monetary system. Especially in China it has been a capitalists system for the past 40 years.
Also China and Vietnam enslaved people!
Russia failed is because it had a planned economy.
China isn't a capitalist country...
And Vietnam isn't a capitalist country...
How can a country be capitalist when the bulk of the industry is owned by the state, has a one party gov't that is dedicated to installing communism, and everyone is required to be educated in Marxism?
Communism and Socialism requires Capitalism...just like Capitalism requires a large workforce and industrial capabilities if not...we would still be serfs and at the very worse slaves...
The communist party in China and Vietnam understands this. Even Marx himself said that only socialism and ultimately communism can occur in a very industrialized country. Therefore China and Vietnam allows capitalist activity within it's economy while maintaining control over capitalist enterprise.
Calling China and Vietnam capitalist is like calling the USA a direct democracy because any US citizen over 18 gets to vote...
USSR failed due to the Cold War, giving into Western military aggression...as the USA engaged in multiple proxy wars and rampant military spending...which Russia desperately tried to keep up with. USSR failed due to the rest of world allowing the USA to threaten the security of the world with wars on every continent due to not liking Eastern Europeans and Asians and Black and Brown people being free from Western imperialism.
USSR decided to reform and eventually disband and gave into the USA's demands because the USSR couldn't keep up with the USA's spending.
I wouldn't say that a country that was nothing but farmland filled with peasant farmers and within a couple of decades after a revolution and WW2, sent rockets into space and industrialized their economy....lifting millions out of poverty...failed due to the nature of their economy...
USSR and China actually proved that a planned economy works..and works better than capitalism at eliminating poverty while at the same time preventing rampant income inequality.