Based is used to describe someone from "Base
Reality" - It comes from the conflicting theories of if we are living in a "Base
Reality" or a "Simulation". The concepts of differing realities (matrix style) gained traction after Elon Musk made the following statements:
1.) From the Recode Code Conference (
2016) There is “a one in billions chance that this that is the world in which we live is base
reality.” Which is to say, not a simulation.
2.) From the Joe Rogan Experience Podcast (2018): "Why would you make a simulation that's boring? You'd make a simulation that's way more interesting than base
reality," Musk said.
A base reality is the idea that there are multiple layers of reality - and those who are from base reality or are "based" (usually associated with common sense and critical thinking) are living with those from a simulation or parallel reality/timeline.