If civilizations can simulate minds and choose to, simulated minds outnumber real ones, so you are probably code. The argument is arithmetic, not mysticism, which is what makes it annoying.
Documented
The trilemma, stated coldly
Nick Bostrom's 2003 paper argues at least one holds: civilizations almost never reach the capacity to run ancestor-simulations, or they reach it and almost never choose to run them, or we are almost certainly living in a simulation. The logic is documented and simple: if capable and willing civilizations run many simulations, simulated observers vastly outnumber unsimulated ones, and a random observer should expect to be simulated. Bostrom assigned no certainty, roughly a one-third-ish credence to the third horn.
Assessment: The argument is documented, logically valid, and explicitly conditional; it proves the trilemma, not the simulation. The premises, substrate-independent consciousness and feasible planetary computing, are assumed, not established.
Stories
Musk, the Matrix, and the glitch economy
The folk version skipped the philosophy and kept the aesthetic: Elon Musk's famous odds, one in billions we are in base reality, glitch videos, deja vu as rendering errors, Mandela effects as patch notes. A rigorous probability argument became a vibe with a fandom.
Assessment: The celebrity endorsements and glitch lore are documented culture. None of it engages the trilemma's actual structure, and a perceived glitch is evidence of perception, which was never in doubt.
Interesting claims
Ancient suspicion, new hardware
The interesting claim is that the argument is old wine at new proof: Zhuangzi's butterfly, Plato's cave, Descartes' demon, and the Hindu maya all assert appearance over reality without the computing. The simulation version is the first that is, in principle, testable, and physicists have proposed looking for lattice spacing in cosmic rays, the universe's pixel size.
Assessment: The lineage is documented philosophy. The proposed tests assume particular simulation architectures and have found nothing; a null result would not disprove simulation anyway. The argument's real achievement is showing that an ancient suspicion can be given modern, valid, and permanently undecided form.
Sources and further reading
Bostrom, Are You Living in a Computer Simulation?, Philosophical Quarterly (2003), the primary text
Descartes, Meditations (1641) and Plato's Republic VII, the ancestors
Zhuangzi, the butterfly dream, c. 3rd century BCE
Beane, Davoudi, Savage, Constraints on the Universe as a Numerical Simulation (2012), the lattice test proposal
Chalmers, Reality+ (2022), the strongest philosophical defense of taking it seriously
Worth asking
The argument says you are probably simulated. Its author says probably not quite. If the difference keeps you up at night, what exactly did you think you were?