I think it is a misunderstanding of the nature of humans that achievements in higher education somehow reflect the level of someone's intelligence rather than the level of that person's ability to apply themselves in academic situations. The professor in your hypothetical conversation is suffering from a superiority complex because he doesn't understand that the fisherman can have a rich and rewarding life without access to all the knowledge that he has. This superiority complex is common where I'm from because people make an assumption that their university qualification makes them smarter than someone without a formal education. The oddity of this is that to some extent the ability to attend university is dependant on your ability to pay for it. So should we judge a persons intelligence by their wealth or academic success when you can be extremely intelligent without either wealth or academic success.
I think that the fisherman without education understands perfectly well the highly educated now deceased professor. The fisherman is probably watching the sunset over the beach, smoking a Gauloises and chuckling to himself thinking, “who's the smart one now?”
The book"Flowers for Algernon" is about a happy but stupid person who receives an operation that makes him much smarter. However, his increased intelligence makes him become less kind and less happy. There are similar ideas in Daoism. However, in modern America, this doesn't seem to be the case. There are a few high-paid professions, like doctors and lawyers, which have a high suicide rate. However, in general, the more education you receive, the less likely you are to commit suicide.
So, a worthless liberal-arts degree can quite literally save your life.