Marxism in all its numerous shapes and guises and forms has had well over a century to demonstrate its superiority. Its greatest "accomplishment" was the murders of over 100 million people by their own government during the twentieth century. The rest of the record consists of poverty, oligarchy, dictatorship, political prisons, show trials, more poverty, shoddy engineering and manufacturing, and special treatment for the vanguard of the revolution.
This is SOP for socialists before a revolution