Why should we care that he’s famous?
Fame doesn’t enter it - the point is Karpathy has about as strong a claim as anyone to having “actually used LLMs for non trivial tasks”.
Reminds me of another famous HN footgun, where some people were arguing about math. One of them backed up his opinion by pointing out that he made it to the Putnam competition, or something like that. The other guy said, "Cool. I won it that year."