How do Jay Gatsby and the Buchannans earn their money?
First, the Buchannans, Tom, Daisy and their daughter live in East Egg, which tells us that Tom’s family has been wealthy for generations. There really is no evidence in the novel that tells us where Tom’s family’s money has actually come from; however, it is evident that Tom works in banking, the stock market, or finance just as Nick Carroway does.
Jay Gatsby, on the other hand, lives in West Egg which tells us that his family is not rich and that he has made his money on his own. Throughout the course of the novel, the reader should recognize that Jay Gatsby has made his money through a series of illegal bootlegging opportunities and has forged many bonds--making his money illegally gotten through his illegal dealings with certain people.