All he cared about was bettering things for himself. He wanted to get the glory of learning the secret behind life. Frankenstein wants to make sure that his name makes a mark in history. In the novel, he says,
A light so brilliant and wondrous, yet so simple, that while I became dizzy with the immensity of the prospect which it illustrated, I was [surprised] that among so many men of genius who had directed their enquiries towards the same scientist, that I alone should be reserved to discover so astonishing secret. (Shelly 50).
He does not think anything bad will happen if he creates a monster, just that he will be recognized as an amazing scientist. After creating the monster, he runs away, causing the monster to become evil. He lets Justine take the accusation of killing William when he knows that the monster was the one who did it. He does not want to get in trouble for creating an evil monster that kills people. Throughout the entire novel all Frankenstein does are things that would benefit him, even if it gets other people