Envy is not selfishness. Selfishness is the desire to have more, regardless of the welfare of others. Envy is the desire for someone else to have less, even if it does not make you better off.

Communism is based on trying to combat selfishness. However, even with enormous well meaning education and reprogramming, selfishness still exists, and selfishness causes communism to fail.

What actually motivates the Communist is envy. This is not what communism is about - it's just that envious people who want others to have less are attracted to the communist philosophy, because the philosophy justifies their desire to steal. It provides a philosophical justification to force others to have less, even if it doesn't actually help anyone.

And this is pretty much what communism produces - mass poverty and hardship (except for the elites).

The phrase which best describes envy is 'shoot the cow' (ie, if someone else has a cow and you don't, then shoot it to make you equal).