I've known lots of intelligent adults who assumed their particular knowledge was common knowledge. Most were polite about it and realized their mistake; a few were quite obnoxious and learned nothing.

Anecdotally, I wonder if/ to what degree this has been affected by increased job specialization, where a person who spends all day working (and perhaps socializing after) with folks who share their particular knowledge and jargon will then err when interacting with folks outside of that bubble.