Socialism never existed in the first place, to ‘fail’. It was a post-feudal, state capitalist venture on the back of a destructive world war, on top of a largely peasant country.
“State capitalism would be a step forward for us.” Lenin
Lenin knew full well, he was warned by the Mensheviks and Martov in particular it would be bourgeois revolution and agreed with this. more info below*)
Socialism is an advanced post-capitalist society, run by democratically us all, building upon a developed capitalism to produce for use and distribute freely.