Do ANY of these socialists realize what a complete failure socialism is?
No they choose not to see the failures of socialism.
A common theme among these people, is that socialism failed because it wasn’t implemented properly. To them, the failures were in the execution, not due to any flaws in the theories of Marx and Engels.
So to them, chairman Mao, Uncle Joe Stalin, Fidel Castro et.al., just didn’t properly transition to socialism/communism.