Victor Frankenstein appears sympathetic and ambitious at first. Everything changes when he decides to create a living creature. His motivation to make a new life was selfish, which he later told Walton.
Detailed answer:
Victor Frankenstein is an ambitious scientist. He wants to create something to make the Earth a better place. Victor’s interest in scientific development became a shameful instrument of his pursuit. His ambitions led him to become single-minded. That is why he abandoned his family and his creation, blaming the Monster for everything.
His motivation for making the beast was to gain personal glory. He was obsessed about creating something that would worship him and his intellect. But he made the Monster lost in his identity issues. Later Victor denies that he is responsible for the creature and the death of his loved ones.
Victor shifts the blame to his creation, burying his feelings of remorse behind a desire for revenge. By the end of his life, he understood everything. He shared his insight with Walton. Victor warned him about the dangerous nature of obsessions and where they could lead. The one thing he did not accept was that the Monster was confused and lonely, not cruel.