If we are in a simulation, then (a) at least one universe, ours, is a simulation; and (b) at least one world includes a simulation with sentience. This gives some evidence that being simulated or being a simulator are not too unusual, and the stack may lead way down to the basement world, the ultimate unsimulated simulator.

In a Tegmark level IV multiverse there is no basement universe but every universe is simulated by some other universe.