What was learned about Socialism in the 20th century

On paper it sounds good: "From each according to their ability and to each according to their needs". Sounds something like maybe Jesus or Buddha might say.

However, in practice people are greedy and self serving so what the ideal looked like in reality in places like Russia and China is a whole lot of poor people treated like Slaves and a few rich leaders "The oligarchs" owning and running everything.

In fact, both Russia and China are still owned and run mostly by Oligarchs today.

So, China understood how important Capitalism was because it is based upon greed. In other words "The harder you work for something likely the more money you are going to make for yourself, your wife and children".

So, it turned out Socialism and communism didn't really work but a newer form where Democracy was wedded to socialism worked much better along with Capitalism.

So, almost nowhere do we find pure Socialism anymore not even in Russia or China. We might find out and out dictatorships like NOrth Korea but Socialism and Communism the way it once was is mostly gone now replaced with varying degrees of capitalism and democracy.

So, most countries have tried to take the best aspects of democracy, Capitalism and socialism to try to make something that will work for the most people so everyone doesn't rebel and kill everyone else.

So, as time goes on other forms of government likely will arise as needed as well by mankind to survive.