Are you sure that the probability that reality being a simulation is identical to the probability that the parent reality is itself a simulation? For us to be in a simulation, we cannot exist in the top-level reality, so let's arbitrarily say 10^100-1/10^100 chance. For our parent reality to also be a simulation, we cannot be in the top reality or the children of the top reality, which should be a slightly less likely scenario. So it seems like the probabilities are not equal.