Yes, exactly, that's the point I'm getting at. We experience "life" through our senses, and our senses can be fooled. Even measuring brain activity requires a subjective level of "trust" that we're seeing a real machine that's taking real measurements, rather than a simulation of a machine. We can look for glitches in the matrix, but absence of evidence isn't evidence of absence.

It's wildly impractical to live your life like that, but at the end of the day we just don't know and probably can't know.