Estella marries Drummle in Charles Dickens's novel Great Expectations because she is driven by a desire for revenge against Pip and a longing for power.
Estella is raised by Miss Havisham to be cold and manipulative, and she uses her beauty and intelligence to hurt others, particularly Pip. She is aware of Pip's love for her and uses it to fuel her own sense of power.
Drummle, while not a good man, represents a type of power that Estella desires. He is wealthy and arrogant, and his social standing is a source of attraction for Estella.
In marrying Drummle, Estella seeks to punish Pip for his love and devotion. She believes that by choosing a man who is cruel and unkind, she can inflict pain on Pip and make him suffer.
However, Estella's marriage to Drummle ultimately leads to her own unhappiness. Drummle is abusive and neglectful, and Estella realizes that she has made a terrible mistake. She is left feeling isolated and alone, and her marriage becomes a source of pain and regret.
Estella's choice to marry Drummle ultimately highlights the destructive nature of her upbringing and her inability to find genuine happiness.
