I worked years with John (like in John Doe). John was a know-it-all. He was a nice person and a good worker, but he was “smarter than the teacher”. That wasn’t a problem for us around him, but it caused a lot of problems for the supervisors.
Once after he had caused a major problem, his department supervisor said “John thinks he knows everything about being a coal miner, and everything about being an astronaut, and everything about everything in between”.