The Jazz Age is presented in chapter three of The Great Gatsby as an age of luxury, opulence (abundant wealth), and hedonism (love of pleasure).
The illegal liquor flows, guests come from everywhere and stay all night, cars are everywhere, the band is many-membered, Gatsby's house is turned into almost a carnival, the library is full of books that are unreadable (the pages are uncut--they are just for show), drunks drive, and recklessness abounds.
And the people thrive on rumors: about Gatsby's business, his war experience, and his past.
Gatsby does not take part in any of this, but at the same time, he is responsible for it all. He does not drink the illegal liquor, but he serves it.
In short, the society in general is irresponsible and shallow.