I don't think you can assume simulated universes would be on the same scale as the real universe. Universe simulations would be very resource intensive and adv

I don't think you can assume simulated universes would be on the same scale as the real universe. Universe simulations would be very resource intensive and advanced civilizations would have better uses for those resources. You may very well get some highly advanced simulations from the advanced civilizations, but they would likely me on a much, much, much smaller scale than the containing universe. E.g., if there are a billion simulated universes, they may each be a trillionth the scope of the real universe. So your odds of being in the real universe are 1/(0.001 + 1), or almost 1. Simulations can't be 100% efficient -- If a system was, I don't think it would be considered a simulation, but just a place in the regular universe -- but even if it were, simulating a solar system would take the full resources of an entire solar system. It's hard to see why an advanced civilization would devote those kinds of resources to creating simulations or if one did, how it would survive for long to maintain it.