This argument always leaves me scratching my head. I can’t see a difference between arguments for our living in a simulator and arguments for George Berkeley’s Idealism. It really seems as if the simulator theory is an atheistic rediscovery of theism, with the word “God” scratched out and the word “aliens” or “future us” written in. And if so, there’s a very long history of philosophy and theology—Descartes’s Meditations come to mind—that can help inform our questioning and experimentation, not to mention ease (or redirect) our fears.