I always come back to this review of Paul Fussell's "Class: A Guide Through The American Status System" when I'm trying to make sense of wealth. I don't know how well it really holds up, but it did get me thinking about the difference between wealth and class. Birkin bags sound like an upper-middle-class phenomenon. The effort involved in trying to obtain a Birkin would go against the spirit of the upper class.
https://www.astralcodexten.com/p/book-review-fussell-on-clas...