Use the noun vanity fair when you're describing someone's over-the-top urban lifestyle, especially if the person has plenty of money and spends it on expensive entertainment and food.
Perhaps you thought it was a glossy magazine, not a life of frivolity. Well it's all that, but in 1678 it was a stop in John Bunyan's allegorical story The Pilgrim's Progress, a never-ending fair in a town called Vanity. After that, Vanity Fair was a widely-read novel in the 19th century by William Makepeace Thackeray, the title of several films, and finally the name of both British and American magazines.