Those people are most likely also up to their eyes in debt, just trying to show off and keeping up with the "true" upper class. Most people in their 20s working jobs won't have substantial wealth, unless they were born into money.
Edit: Not talking about the guy who rents a $10k apartment he can't afford to trick people into thinking he's rich. Talking more about people buying into social strata they can reasonably or paying fealty to those in higher strata to benefit their career. It is a thing out here.
The guy I had in mind was, I think, 29, german and I think working at BCG? Very polished. Had his fresh-to-the-city model girlfriend and threw great parties.