The setting of the Great Gastbytells us a lot about the American dream. The novel takes place during the roaring twenties, when wealthy Americans were living in excess, and conspicuous consumption was the norm of the day. This vision of limitless excess was tied to the American dream in an important way.
There was an implicit notion that if you worked hard enough, you could make it. Moreover, you could have a certain type of lifestyle. This last point is an important point to keep in mind, because the American dream is in many ways a lifestyle.
Jay Gastby is the perfect example of this. He was from humble beginning, but through determination and unsavory means (being a bootlegger), he was able to make it big.