Playing billiards and having tons and tons of books. I also forgot to add chess in particular.
People can possess enormous collections of books, and do, but I really bet them that they don’t pick up to read a single one. Only to sometimes bring up certain lines to win online and pointless arguments over.
Billiards is usually a bar/pub kind of game, but some others seem to associate it with intelligence. You don’t need to be intelligent to play billiards.
Chess is self-explanatory. Lots of people throw around the line of “people are playing checkers while X plays chess” and other similarities. I think people look way too into chess as being a measurement of intelligence.
The Great Gatsby is 100 years old. I’d assume that books were still more expensive back then relative to people’s incomes, and they were also the only way to access that content while today you have e-books, PDFs, YouTube-videos or even websites, which are often available for free (not necessarily legally).
On top of that, many literary devices are unrealistic or exaggerated.