The more we use LLMs to act as proxies for our thinking the less we have of one particular thing that makes us distinctly human. While LLMs can be directed to simulate it much in the same way it can clone writing styling or art styles is precisely the same we can so impoverish the breath of human expressiveness that it would soon be prized above others.
Personality.
Each living and breathing person is as unique in their diverse experiences as is their retinal pattern or hand vein pattern. How we have arrived at our current moment in life shapes how we communicate our unique perspectives and relinquishing that over to AI makes us all the more poorer for it.