Because we are in a dream
That guy is a fucking moron, and clearly doesn't understand how computers work for shit. The idea of simulating every atom in the universe with a computer system is just plain dumb.
How are we able to know there is absolute truth though?
I used to have that too when I was in kindergarten.When I was a kid, I used to imagine everyone in the world was a robot and I was the only human. I have no idea why.