In this episode of Masters of Scale, Reid Hoffman interviews Simon Sinek, author of "Start With Why," about finding purpose in business and life. They discuss the balance between mission and financial incentives, the importance of "why" in appealing to early adopters, and the distinction between mercenaries and missionaries in Silicon Valley. Sinek emphasizes the significance of building great leaders by focusing on their characteristics rather than just mission success. They also explore the scaling of ideas, the cultivation of optimism during difficult times, and the critical role of friendship as a "biohack" for happiness and resilience, cautioning against the potential pitfalls of AI friendships that lack mutual investment and struggle.