An important puzzle in the study of political violence is why individuals risk their lives fighting for a public good, when they can free-ride and enjoy the same benefits if others take the risk. This logic is particularly important to rationalist theories, which view risk as an inherent cost to violent armed group participation—which has to be offset by selective incentives, peer pressure, or coercion. This perspective has widely contributed to the understanding of violent conflict, but ignores key insights from psychology. What if risk is not a cost and instead attractive? In this article, I argue that people with a sensation seeking personality—interested in novel and intense experience and willing to accept risk for the sake of it—are more likely to join armed groups. Preliminary survey evidence comparing voluntarily and forcibly recruited members of Colombian armed groups supports my argument. The re-interpretation of a series of existing studies on Colombian guerrilla and paramilitary fighters illustrates the pervasiveness and varying manifestations of sensation seeking. Personality traits are an under-recognised ingredient in the process of joining armed groups and complement our current understanding, which is mainly determined by contextual conditions and situational motivations.