F. Scott Fitzgerald's magnum opus, The Great Gatsby satirizes the materialism of what Fitzgerald himself named the Jazz Age. Indeed, the characters worship at the altar of greed: Daisy's voice sounds like money and she has been purchased as a wife for a $350,000 pearl necklace;Tom Buchanan brings dozens of polo ponies with him from Chicago to East Egg and proudly displays his property to his guests; Jay Gatsby re-creates himself and amasses a fortune merely for the sake of having one to display to win back the past and Daisy; he offers his rewards for his illegal greed by hosting lavish parties where no one knows any one else, parties which Jordan Baker describes as "so intimate" because "there isn't any privacy." Meyer Wolfshiem sells his soul for gambling upon the World Series; Jordan cheats in order to win golf tournaments and prizes; Mrytle Wilson gives herself as human sacrifice to the false pretenses of money.
After the death of Mrytle Wilson, Jay Gatsby is the only rich man who demonstrates compassion for anyone else, causing Nick to remark that he is "worth the whole damn bunch," of the "careless people" whose immoral materialism and greed are incurable.
Greed is defined as the excessive and extreme desire for something, often a lust for more than one needs or is entitled to. The novel exposes a few examples of such avarice.
Most pertinent is Jay Gatsby's excessive desire for Daisy Buchanan. He goes to extreme lengths to draw her close to him. She has become his ultimate goal, his sole purpose, his holy grail. The fact that he becomes involved with sordid characters from the criminal underworld and indulges in illegal practices to amass a huge fortune indicates the depth of his desire. He is single-minded in his purpose and draws others into his grand scheme to once again gain Daisy's affection and win her over. He, for example, approaches Jordan Baker to approach Nick Carraway so that he may arrange a meeting between himself and his grand ideal.
The fact that Jay garners such a great fortune is not greed in itself, but an element thereof, for he does not care much about his wealth as much as he cares about what he can achieve through it. It is a means to an end. Jay realises that Daisy has married into old money and in order to win her back, he has to either exceed his competitor or, at least, be his equal in material terms. It is for this purpose that he builds a huge mansion and throws excessive parties. These are attempts to draw Daisy closer and, at the same time, impress her. When he takes her and Nick on a tour through his mansion and displays all his beautiful shirts to her, he is essentially making a statement that he has 'arrived' and can give her just as much as her husband, Tom, can.
Jay is partly successful in achieving his goal. He gets together with Daisy but his final attempt to win her from Tom ends in failure. During his confrontation with Daisy's arrogant husband, he sees her drawing further and further away from him, especially when Tom appeals to the affection that they shared on their honeymoon. Jay is a beaten man. The partial achievement of his dream is what tragically leads to his demise. After the confrontation with Tom, he and Daisy leave in his car and she accidentally kills Myrtle Wilson while driving. This tragic incident ultimately culminates in Mr. Wilson shooting Gatsby and then himself. Gatsby's excessive desire for Daisy also spelt his doom.
References to Meyer Wolfsheim, a sordid underworld character, also alludes to covetousness. Wolfsheim apparently fixed the World Series, which implies that his desire was more wealth, obtained by hook or by crook. The purpose was to get richer. He was the one who recruited Jay into the dirty world of money laundering and the sale of fake bonds, thus introducing him into a dangerous society of criminality where money was valued more than a person's life.
Jordan Baker cheated during a professional golf tournament by adjusting the lie of her ball. Her actions display her greed for winning and its resultant financial reward. Although Nick felt affection for her, it is this kind of dishonesty which probably caused him discomfort and culminated in their relationship ending.
Finally, it is Daisy's greed for wealth and status that informed her decision to marry Tom Buchanan when he proposed when Jay was absent, soldiering away during the war. Although she felt for Jay, Tom's proposal was too attractive to resist. She would marry into old money and would enjoy a life of privilege and luxury. A more damning indication of her materialism is her reticence, firstly, to leave Tom when she discovered his affairs and secondly, her refusal to finally be with Jay and abandon Tom. It is this refusal that gave Tom the upper hand. He could then use his influence over Mr Wilson by subtly implicating Jay in Myrtle's death. Wilson, overcome with bitterness and vengeance then murdered Jay.
In the final analysis, then, it is the integration of all these aspects of greed which led to and ultimately resulted in a most tragic outcome.
I would consider the most obvious example that of Daisy who wasn't capable of waiting until Gatsby got back from Europe and needed to feel the comfort and security of great wealth. This was at least part of the reason she was attracted to Tom and it could certainly be argued that it ruined not only her life but Gatsby's as well.
Gatsby's greed and hunger for things he cannot have, such as the approval of Daisy and her crowd that can only come from having old money, or for Daisy herself leads to ruin for Gatsby and for Daisy in some ways. You might also make the argument that it leads to ruin for Wilson and Myrtle as their great conflict leads at least in part to Myrtle's death on the road.