First, when Nick first went to Daisy's house, Buchanan spoke in a rough voice. He is rude and gives the impression of being overbearing. He looks down on those who want to climb the upper class through struggle. Buchanan has a romantic life everywhere. Even when his daughter Pami was born, it was "God knows where Tom was fooling around with who". There are only a few writers, and the image of overbearing, rude and indulgent is vividly on the paper.
Secondly, Buchanan led Nick to a private dance and hooked up with a married woman, Mertel, just because "they can't stand the object of their marriage". Stimulated by drugs, Nick and Buchanan completely forgot where they were. Coupled with alcohol and beautiful women, an out-and-out constantly chauffeured demeanor was revealed.
Thirdly, Buchanan looked down on Gatsby, thinking that Gatsby was just an upstart who desperately wanted to enter the upper class, and especially could not tolerate Daisy having a relationship with an upstart from the lower class. Because of this, when Gatsby and Buchanan showdown, Buchanan revealed that Gates "I thought he was a bootlegger at first sight, and I was really right." "We were born different. It can be seen that Buchanan is good at calculation.
Fourthly, after Daisy killed Matt with her car, in front of the grieving Wilson, she clearly had an affair with Matt, but she put all the suspects on Gatsby, which directly led to Gatsby's death and Daisy's elopement, which showed that she was insidious, despicable and irresponsible.
Buchanan represents a class that Gatsby wants to be but can't fit in. Gatsby's life is a life of abandonment and abandonment. Since he changed his name at the age of seventeen, he abandoned his birth and family, then repeatedly abandoned by Daisy, abandoned by his diners, and finally abandoned by the class represented by Wilson, thus completing his tragedy and becoming a person without belonging.