So, if the universe is indeed a simulation, who exactly is simulating it?
Well, so long as we're not a random bit of noise as a result of quantum reality, we can assume that there's some kind of conscious intelligence writing the code.
It's tempting to picture some kind of science fiction inspired race of super-intelligent, pan-dimensional beings in futuristic hats, but the likelihood is that our virtual reality was probably programmed by, well, humans. Or at least the "real" version of humans.
Much like we have a propensity to create the people we know on The Sims, it stands to reason that a civilisation with the ability to run complex simulations would create something like themselves. Perhaps these simulations are even being used to predict events in the "real" world, perhaps the future human race is simulating its past, as a form of digital archaeology.
If you want to get really meta, perhaps the simulators are simulations themselves. It's just simulations all the way down.