One of three unlikely-sounding claims about reality has to be true

Philosopher Nick Bostrom argued that at least one of three things must hold: almost all civilisations go extinct before they can simulate their own history in detail, or those that survive choose not to run such simulations, or we ourselves are almost certainly living inside one right now. He never claimed the third option is true — only that logically, one of the three has to be.

— Nick Bostrom, Are You Living in a Computer Simulation? — Philosophical Quarterly, 2003