Victor created the monster because of two main reasons; the death of his mother, and wanting his name to go down in history. Frankenstein's mother died at birth, so he had to live his whole life without her. He thought by being able to create life, he wouldn't have to go through the grief of a loved one ever again. Instead, he would just bring them back to life. Getting everyone to know his name was also a big goal of his. He wanted to go down as the man who found another way to create life. Both of these goals made him crazy, which is what gave him the drive to actually create the monster.