That's true. That said, what can be found online does cover a lot of what offline people do and think and write, since there is a lot of stuff being brought on

That's true. That said, what can be found online does cover a lot of what offline people do and think and write, since there is a lot of stuff being brought online that wasn't produced online (books, news, ...) Otoh, it's not clear how (or if) LLM training balances the different sources