Tom Buchanan hates Jay Gatsby because of Gatsby's feelings for his wife, Daisy. Throughout the novel, Tom is the antagonist and Gatsby is the protagonist. Their confrontation over Daisy and Gatsby's criminal past is one of the novel's climaxes.
Daisy Buchanan is the love of Jay Gatsby's life. When Daisy rejects Gatsby and chooses Tom Buchanan for the status and wealth he can provide her, Gatsby is driven to make money. Tom's family wealth and social status is a contrast to Gatsby's wealth obtained through racketeering. Gatsby's reunion with Daisy leads to the climatic confrontation between Tom and Gatsby at the Plaza Hotel in chapter seven.