Why does the novel end with Gatsby's funeral?

The novel ends with Gatsby's funeral to highlight the tragic emptiness behind his glamorous life and the failure of his dream. Despite his lavish parties and wealth, very few people truly cared about Gatsby or showed up for his funeral, emphasizing his isolation. This contrast underscores the hollowness of the American Dream Gatsby pursued—his idealized vision of reclaiming the past and winning Daisy ultimately leads to his lonely death. Nick's reflection on the funeral and the green light symbolizes the disillusionment with the dream and the moral decay of the wealthy world Gatsby inhabited.