When I got out of school I went to work for Oracle and decided to read the database manuals, even though I wasn't working on database stuff. When I left I read other database manuals and was able to help people code database stuff, not because I was a real database expert, but because I had read the manuals and they hadn't.
I think something similar is going on here? For some subjects and some questions, ChatGPT acts like a co-worker who has read all the manuals, and that's enough.