Friedrich Nietzsche's personal philosophies challenged societal norms by critiquing established morality and religious beliefs. His concept of the Übermensch and the idea of will to power urged individuals to transcend traditional values and create their own. Nietzsche's experiences with mental health issues and societal rejection fueled his disdain for conformity and the herd mentality. His proclamation that "God is dead" highlighted the need for individuals to take responsibility for creating meaning in their lives without relying on external authorities. This radical rethinking of values and existence influenced modern philosophy and existentialism.