The main reason is the mechanics of how it works. Human thought and consciousness is an emergent phenomena of electric and chemical activity in the brain. By emergent, I mean that the substrate that composes your consciousness cannot be explained only in terms of those electric and chemical interactions.
Humans don't make decisions by consulting their electo/chemical states... they manipulate symbols with logic, draw from past experiences, and can understand causality.
ChatGPT and in a broader sense any deep learning based approach, does not have any of that. It doesn't "know" anything. It doesn't understand causality. All it does is try to predict the most likely response to what you asked one character at a time.
Humans don't make decisions by consulting their electo/chemical states... they manipulate symbols with logic, draw from past experiences, and can understand causality.
ChatGPT and in a broader sense any deep learning based approach, does not have any of that. It doesn't "know" anything. It doesn't understand causality. All it does is try to predict the most likely response to what you asked one character at a time.