It's not as funny when you get to live under the rule of well trained Marxists. Hundreds of millions of them have been produced over the last century. Look into a history book or just ask around.
It turns out that some genocidal ideologies are too hard to let go, we managed with Nazism pretty well but Marxism is taking some time. Cambodia under Pol Pot should have been enough.
Indeed it is surprising, but I think it's because communism wasn't put on trial when the Soviet Union collapsed. There weren't courts punishing gulag wardens and KGB officers for torture, murder, and everything else under the sun. Everything was forgiven for the sake of peace, but everyone learned the wrong lesson. Which is why when "nationalism" is mentioned, people think of Nazi germany, but when "socialism" is mentioned, today's youth especially wants to think of Sweden. The crimes of Nazi Germany are regularly mentioned in popular culture, but those of Communists not so much, though they're more contemporary, lasted much longer, and arguably affected a lot more people.