Lady Macbeth wanted to kill King Duncan primarily to seize power and fulfill her ambitious desires. When she learned about the prophecy that her husband, Macbeth, would become king, she was consumed by the idea of power and the throne. However, she doubted Macbeth’s resolve and willingness to take action to achieve their goals.
In her view, Duncan was a benevolent and virtuous king, but he stood in the way of their ambition. Lady Macbeth believed that in order to elevate Macbeth to the throne and satisfy their aspirations, they must eliminate Duncan. Her ambition drives her to manipulate Macbeth, questioning his manhood and courage to spur him into committing the murder. She believed that once Duncan was out of the way, they could enjoy the power and status that would follow. This act symbolizes not just the ambition of Lady Macbeth, but also the destructive nature of unchecked ambition, which ultimately leads to chaos and downfall.