Men (not) working: The idle rich in Fitzgerald's novels

Of course when we read a Henry James novel, or story, we don't expect anyone to seriously engage in work - the characters sometimes are described as businessmen or bankers and so forth, but they never seem to have to spend any time at the office and the nature of their work is entirely peripheral to their lives as literary characters. In a word, they're rich. And James doesn't care about how they got to be rich, though there's always a whiff of snobbery - much better socially to inherit money (and titles) than to have to earn it (or have your grandfather earn it for you). But what about F. Scott Fitzgerald? His novels are much more truly American, and The Great Gatsby, for one, is all about making money (not necessarily by working) and creating illusions of wealth, titles, and nobility. And yet - Nick doesn't seem to have to spend a whole lot of time at the office, or thinking about the office. Maybe work was completely different in those days - well-off Yale or Princeton graduates weren't expected to "work" more than a few hours a day, but they brought money into the firm just by who they were and whom they knew - everything connection made is work. Am now reading "Tender Is the Night," and struck by Fitzgerald's assiduous insistence that the narrator, Dick Diver, is a dedicated psychiatrist, even writing a book or two. Of course it's obvious to every reader that he's not writing about Diver and Nicole Warren but about himself and Zelda, and the references to Diver wanting to be a great doctor are coded references to F's wanting to be a great writer - however, it's curious, we know F. worked very hard at his craft, at least when his head was clear - but why is there then such a sense of waste and idleness among his characters? If he goes to the trouble of writing about a doctor, why does he know, or show, so little about medical practice - this guy seems to have nothing to do (I'm only in part 2, 60+ pages in) but take jaunts around Europe and gab on the beach. Nobody works, they just quip. Is it an innate inability to write about the work life of a character? Did people actually live this way? Or is there some thematic reason why Fitzgerald (and James, too) feel compelled to convey their (American) characters as idle and feckless?