I think that it would be impossible for us to know either way. However statistically speaking, the probability that at a given time in the future, sufficient computing exists such that simulating humanity in its entirety is possible within a computer system. This computer system in that far future would be no more power than the equivalent phone , so , it wouldn't be difficult to have many simulations. It stands to reason that there exists only one true world, and the rest are all simulations. We can also theorize that simulations can exist within simulations making the probability even more that we are living in a sim.