I disagree with your fundamental premise. The fact that a machine trained on billions of real conversations online can mimic reasoning does nothing to alter my understanding of self. And you haven't given any argument as to why it should.
This is the crux of the debate, right? Whether it's doing mimicry or reasoning. I struggle to see how you could view it as purely mimicry. It has to tie together multiple novel thoughts in a logical construction to create its responses.