There's a correlation that smart people study things they find interesting. As soon as it became clear that computer science was a money maker, you had a lot of students taking doing CS majors who weren't really interested in anything except making money.

Majoring in anything other than CS, engineering, finance, business, or biology (premed) is a signal for intellectual curiosity. Obviously there are plenty of students with real curiosity in those majors too, but there's also many incurious mercenaries.