Elon Musk thinks there's a one in a billion chance we are living in a "base reality." If a set of advanced VR goggles were slapped over your eyes the moment you were born, imagine them being removed on your 50th birthday. Here are two (of many) ways to think about it:
1. As the rate of technological development increases exponentially, it is highly likely that in the not-too-distant future, civilization(s) will possess the ability to generate sufficiently real simulations such that humans can't tell the difference between them and reality. Further, it is likely that these civilizations, at some point, will wish to simulate societies of the past, just as we would if it were not prohibitively difficult. As such, assuming a nearly-infinite number of these simulations are run, is it not likely that we/I/you are living in one?
2. Consider the current video game series, The Sims. These are virtual worlds in which we, as humans, create societies according to our whims. It is not out of the realm of possibility that, with exponential increases in technological advancement, characters in games like The Sims begin using and subsequently building computers. It is further possible that these simulated computers become sufficiently powerful to the point that they, themselves, can support games like The Sims. This could occur (or have been occurring) ad infinitum. If one were to throw a proverbial dart at this nested bundle of simulations within reality, what is the probability that we/I/you exist in the outer-most shell/reality?
Just because something is possible does not make it likely. There is nothing to indicate the world is a simulation, Nor obvious motivation for it to be one.
If it were a simulation then it would stand to reason that the thoughts and feelings you have are also a simulation, That you do not truly exist. This makes more sense than assuming that we are real, But the world we navigate is not.
I understand the desire for one to ascribe to a sort of creator, Or a feeling of something beyond ourselves, But I think this is just an aspect of humanity which drives us forward and has lead us to the great achievements we have accomplished and the seemingly silly conclusions, Like belief in God or a simulated world.