The central obsession in The Great Gatsby is Gatsby's obsession with Daisy. This is the reason for Gatsby's existence and for the novel. It feeds the plot, the themes, the conflicts, the imagery, and the illusions.
Daisy is obsessed with security, success, money. Whether one sympathizes with her because she is a female trapped in a patriarchy, or condemns her for being greedy, the obsession is still central to her character.
Tom is obsessed with his stature, his place in society, his image, his success, and with maintaining the status quo.
These obsessions conflict and fuel the narrative. Though figuratively all of these obsessions may be illusion, in the end, literally, Gatsby's obsession is proved an illusion, while Daisy's and Tom's obsessions survive.
To a great extent, the concept of "obsessions" is of vital importance in Fitzgerald's work. On one hand, Gatsby's obsession with Daisy has been definitely noted. Through this obsession, his drive for material wealth emerges. For the entire flapper social set of Tom, Daisy, and Jordan, their obsession is with a lifestyle that revolves around parties, social gossip, and a type of self indulgent lifestyle regardless of cost. This obsession causes them to use people as means to ends as opposed to ends of themselves. On another level, the different types of love featured in the work are obsessive and self serving loves. It is rare that the reader sees a love that is not obsessive, not driven by love of self. Fitzgerald might be making a statement on how the time period viewed the concept of love as more of an expression of one's own sense of self than a true merging of separate identities into one.