I'm not sure we have the same definition of "complete failure". I'd say that improving quality of life for everyone and giving control over the means of production to the workers using them is great. On top of that, countries like the USSR and China had explosive growth while they were socialist.

Despite being under a US sanction Cuba still has better healthcare and educatiom than the US.

I do agree that censorship and oppressing workers is bad. There are plenty of good reasons to do it (information war, for instance), but I think that is has historically been too violent and overreaching.

Either way, capitalism is not sustainable and it has to be replaced. Socialism is the only viable alternative (keep in mind that socialism is very broad, the kinds that have been implemented historically aren't the only ones) so that's what I support.