Actually it technically goes all the way back to Rene Descartes and his "deceiving demon" scenario. The principle is exactly the same, but Descartes is at least grounded in reality...he recognizes that there's a consciousness/experience issue, and that while one cannot assert that reality is not a fabrication/illusion, you can assert your own personal existence (cogito ergo sum). The computer simulation is just the latest feasible model for suggesting we cannot trust our experiences to represent actual reality.
For this to be a computer simulation, knowing what we know, it implies at least the following:
1. the simulation can not only simulate the physical world, but can also simulate consciousness
2. Our definition of consciousness as simulated excludes the existence of external awareness, suggesting we're all part of the program. But if the program is being experienced by programmers/users anyone reading this who is not a progammer or user is likely not "real" in the conventional sense
3. However, since we know we are conscious, or programmed to think we are, then it raises questions about the definition of both this awareness and actual sentience. In fact it cascades into a whole mess of questions that soon leads to the same line of thought about how our universe works, how we relate to it, and where it came from. It is almost tautological, in fact....
4. Leading to the notion that if a simulation is sufficiently indistinguishable from "the real thing" then how do you recognize when you're in the real world vs. the simulation?
5. And if it is a simulation, all it proves is that there's an operant higher level of reality which we haven't ye developed an empircal method of detection for, and may never be able to due to programming issues
6. And if that's true, then we're back to square one, with Descartes' demon, realizing that the only certainty we have is that we are able to perceive our self-awareness --even if that self-awareness could be a simulation, it is still something we each indelibly hold in our personal experience to be the point of definition for who we are, regardless of our sensory experiences. ....So yeah, from the philosopher's view all Elon Musk has done is reframe the question Descartes already posed with a more contemporary framework.