I am not an expert, but from what I understand, everything is supposed to exist in all states. Observation allows us to observe specific aspects or states, which makes it appear like observation changes outcomes, when it is just as likely tht some states are more easily observable than others. Anyway, it is just as possible that observations made only appear to be a simulation, due to the variability of what can be easily observed. In shot, the idea of the universe being a simulation may be an illusion in itself.

I try not to spend too much time thinking about it, as I'd rather enjoy living my life than spend it contemplating aspects of existence that are not likely to be proven either way in my limited lifetime.

If the universe is a simulation there's nothing we can do about it. The nature of reality does not keep me up at night.