By the end of the story, Victor loses all his humanity due to his desire for revenge. The monster killed everyone the scientist loved, making the wrath even worse.
At the end of Frankenstein, Victor becomes angry at the monster because he destroys the scientist’s life. His enthusiasm fades away as the story progresses. He is no longer striving for the initial goals. Victor states: “You can blast my other passions, but revenge remains—revenge, henceforth dearer than light of food! I may die, but first you, my tyrant and tormentor, shall curse the sun that gazes on your misery.” In other words, in the end, Victor only wishes to kill the monster and asks Walton to complete his last request even after the scientist’s death. The main character was passionate about restoring life among the dead. But he inevitably becomes hateful of his creation. The loss of his loved ones is the key reason for such an emotional response. Some portion of his anger could be aimed at himself. After all, he was the main catalyzer of the events. The scientist loses all that makes him humane, and he becomes an empty shell with the sole purpose of eliminating the monster.