If you think it’s highly likely we’ll be able to simulate reality to the point where it’s completely indistinguishable from actual reality (say, 400 years from now), then we’re probably already living in a simulation.
Just as a matter of probability, convincingly simulated realities, if they ever come into existence at all in the future, will massively outnumber the singular ground reality.
So it’s not just plausible, but seriously probable–indeed, overwhelmingly likely–that the eighty years you experience subjectively is actually a month (or less!–minutes? seconds?) of data crunching in a computer in the ground reality. What you take to be wetware (neurons firing electrically and chemically over eighty years in your meat computer, generating consciousness and experience) is more likely dry wire in a computer existing in the singular ground reality, a thousand years beyond where you think you actually exist in history right now. It may be, say, the year 3016, not 2016.
Again, if you take simulated reality indistinguishable from actual reality to be an inevitable part of the human future, then this conclusion seems inescapable.
Here’s Joshua Rothman at The New Yorker:
[S]imulated human consciousnesses could vastly outnumber non-simulated ones, in which case we are far more likely to be living inside a simulation right now than to be living outside of one.
Superficially, the simulation argument bears some resemblance to the one made by René Descartes, in the seventeenth century, that there could be an undetectable “evil demon” shaping our perceptions. But, where Descartes’s argument was essentially about skepticism—How do you know you’re not living in the Matrix?—the simulation argument is about how we envision the future.