It tells you no such thing. In a distributed system if you take out the main ethernet switch (interconnect) you can bring the whole system to a halt, but that doesn't mean the computation happens there.
Now, no kidding: there's a massively parallel (80 G neurons x 10^ fanout) machine with a ~ 100 Hz clock inside your skull, but there's a lot of computation going on elsewhere. Look at what I said about all the neurotransmitters in your gut, not to mention the rest of your reticulated nervous system. And people do plenty of things all the time (e.g. hit a baseball) that require a response and feedback faster than the nervous system can transmit from the big bag o' neurons to the wrist.
I'm not saying you're wrong; I'm saying there's far, far from enough evidence in contemporary neuroscience to support the level of confidence you exhibit in your theory of mind.
The brain is extremely sensitive to status across the rest of the body, but based on amputations and circumstances involving life support, viral pathology and hypoxia, there’s strong evidence that time keeping and concept of self sit just above the floor of the brain pan, near the optic nerve’s main cross-over, between the ears. (give or take and inch or two)
No one who makes these types of arguments can justify why they continue to defend their side of the argument if nothing they do matters.
If you truly believe that you do not exist, explain it to me in a way that does not assume your existence. Most of these arguments start with the two words that the most famous argument for existence does, "I think therefore I am".
It doesn’t mean a little person reclines in a hammock there, but I’d wager that there’s a resonant, sensation-event-sensitive waveform, that has a primary focal node looping through a region very close to the pituitary gland in normal, living human beings (with similar analogs in all other mammals, and also many other vertebrates), also hinted at by the pituitary’s role in endocrine governance.
But furthermore, you deny your own agency, if you refute me. I suppose maybe you are simply a bot on the internet, then. In which case, I'm deeply disturbed to find entities on the internet telling me I'm not sentient. Maybe having humans inform me of the same poorly rationalized fallacy is worse?