Nick Bostrom argues that at least one of the following statements is very likely to be true:

1. Human civilization is unlikely to reach a level of technological maturity capable of producing simulated realities, or such simulations are physically impossible.
2. A comparable civilization reaching aforementioned technological status will likely not produce a significant number of simulated realities, for any of a number of reasons, such as diversion of computational processing power for other tasks, ethical considerations of holding entities captive in simulated realities, etc.
3. Any entities with our general set of experiences are almost certainly living in a simulation.

this.