Would answering the question of whether we're in a simulation have any impact on your behavior, thoughts, and actions? Probably not. So what does it matter?
If we could prove (or even make a strong, but unverifiable argument) for or against the claim that we live in a simulation, then that would have a real-world effect.
A concrete example: if we knew we lived in a simulation, and therefore knew that the simulation of an entire universe were possible, we'd probably expend resources on research and engineering efforts to create such a simulation.