It's because you and I also have mental resources that are structured very differently from ChatGPT. Even if some part of our brain might resemble a LLM, a LLM is a very poor representation of other parts of the brain. If you take ChatGPT too far, it falls into repetition and demonstrates that it obviously has no comprehension of the material it's remixing.

Maybe some combination of a LLM and other mental machinery would result in AGI with real comprehension.