The difficulty I have with the "universe as a simulation" hypothesis is that it pre-supposes a fundamental difference between simulation and reality, which I strongly suspect is not the case. Everything we have observed about our physical reality indicates that it is 1) composed of mathematical structures and 2) it is computable.

Given these characteristics it is clear that the universe we experience could be executed by any system capable of computation [Universal Raspberry Pi if you will :)]. As such, it is highly likely (almost a certainty) that whatever more foundational reality exists outside of our experience it is very different than ours and is responsible for the computational effort that generates the universe we experience. Given that any physical system is capable of computation when properly organized one could easily imagine a higher dimensional structure that did not require an intelligent being to build it that just "happens" to compute this reality.

Would that be considered a "simulation"? Or is a simulation something that requires an intelligent being to build it? Obviously this turns into a bit of semantics.