Based on the existing literature on worldview beliefs, cynical hostility, and Machiavellian cynicism, we suggest that holding cynical beliefs about human nature can be detrimental for individuals' income. Cynical individuals are more likely to avoid cooperation and trust or to overinvest in monitoring, control, and other means of protection from potential exploitation. As a result, they are more likely to forgo valuable opportunities for cooperation and consequently less likely to reap the benefits of joint efforts and mutual help compared with their less cynical counterparts. Studies 1 and 2, using nationally representative longitudinal surveys of the American population, show that individuals who endorsed cynical beliefs about human nature at baseline earned comparatively lower incomes 9 (Study 1) and 2 (Study 2) years later. In Study 3, applying a multilevel model of change to a nationally representative panel study of the German population, we show that cynical beliefs at baseline undermined an income increase in the course of the following 9 years. In Study 4, the negative effect of cynical beliefs on income proved to be independent of individual differences in the Big Five personality dimensions. Study 5 provided the first tentative evidence of the hypothesized mechanism underlying this effect. Using survey data from 41 countries, it revealed that the negative effect of cynical beliefs on income is alleviated in sociocultural contexts with low levels of prosocial behavior, high homicide rates and high overall societal cynicism levels. Holding cynical beliefs about others has negative economic outcomes unless such beliefs hold true.