How do we know that everyone on the internet isn't just a bot?

I mean, there might be a secret AI technology that is so advanced to the point that it can mimic a real human, make posts and comments that looks like its written by a human and even intentionally doing speling mistakes to simulate human errors. How do we know that such AI hasn't already infiltrated the internet and everything that you see is posted by this AI? If such AI actually exists, it's probably so advanced that it almost never fails barring rare situations where there is an unexpected errrrrrrrrrorrrrrrrrrrr.............

[Error: The program "Human_Simulation_AI" is unresponsive]