The human mind is _so much more_ than a prediction machine, and incredibly complex... All that's before you get into the way the endocrine system interacts with your mind.
A single neuron has an average of 250000 connections in some parts of the brain. The speed at which neuronal signals travel varies neuron to neuron from 2.5m/s to 200m/s.
Human minds are more than just prediction. The anterior lateral prefrontal cortex has the sole responsibility of prediction (not that nothing else does, just that the ALPC seems solely dedicated to that task) and is extremely good at it. Prediction can influence all sorts of mental processes such as most all forms of perception... But it is _not_ the same as _being_ all forms of perception. If something unpredictable enough happens in front of you: you'll still see it.
Sure there are limits to that: when focused on a task the predictive parts of sight tend to filter out visual data that doesn't match the signal you're looking for (see: basketball players passing the ball and a moon walking man in an ape suit) but if every basketball player turned into Spaghetti-os and started screaming you'd still hear the sounds and see the O's.
So sure: LLMs do a good job at basic prediction but they're nowhere near the complexity of the human mind, of which prediction is only a small piece.
(And let's not even get into efficiency... A brain runs on 20W of power)