Most of the people who get sent to die in wars are young men who've got a lot of energy and would probably rather, in a better world, be putting that energy into copulation rather than going over there and blowing some other young man's guts out.
Because our entire universe is made up of consciousness, we never really experience the universe directly we just experience our consciousness of the universe, our perception of it, so right, our only universe is perception.
Of course, Marxism is an example of what Carl Popper would have called a 'World Three' structure, in that it's got immense power as an idea, but you couldn't actually hold up anything in the world and say: 'this is Marxism'.