There is also a lot more that one could say about rain: dry adiabatic lapse rates, phase transitions, the role of dust and aerosols as a nucleation site, Clausius Cleyparon, and the ilk would be natural things for this persona to talk about. Instead it sounded like SEO spam on steroids.
It probably haven't had much practice. It's not like the internet is shock full of texts tagged with the IQ of the author. It is, however, full of SEO texts, Wikipedia articles, and /r/askscience answers.
There are also 1 in 6B people with an IQ of 200 or above, and I imagine they're not prefacing every public forum interaction with: "I have an IQ of 200, here's my take on..."
Unless I'm mistaken, chatGPT is trained on word embeddings, so it can't really make spelling mistakes, unless those misspelled words are included in the vocabulary.