An interesting argument against simulated universes is that simulations tend to be skin deep. Thus, if you are making an episode of the Simpsons, you don't actually have to fill their kitchen with everything they might need for the week, or provide them all with clothes ditto. This is because simulations tend to deal in appearances, see video games.
So in a video game, you might have a large explosion, kapoww, and so on, but you don't have to fill in the chemical and physical things going on in an explosion, down to a microscopic level. In fact, you probably couldn't do it, as the information required would be massive. But there's also no point.
Well, you can get round this argument of course, by suggesting an hugely intelligent species, with very advanced computing techniques, so not only would they want to fill in the microscopic detail and the long periods of time required, they would have the means to replicate this.
So your bored teenager in his mum's basement on a distant planet, is even now simulating the exact shade of spray tan on a Strictly contestant. Why wouldn't he?