Hate is widespread online, hits everyone, and carries negative consequences. Crowd moderation—user-assisted moderation through, e. g., reporting or counter-speech—is heralded as a potential remedy. We explore this potential by linking insights on online bystander interventions to the analogy of crowd moderation as a (lost) public good. We argue that the distribution of costs and benefits of engaging in crowd moderation forecasts a collective action problem. If the individual crowd member has limited incentive to react when witnessing hate, crowd moderation is (...) unlikely to manifest. We explore this argument empirically, investigating several preregistered hypotheses about the distribution of individual-level costs and benefits of response options to online hate using a large, nationally representative survey of Danish social media users (N = 24,996). In line with expectations, we find that bystander reactions, especially costly reactions, are rare. Furthermore, we find a positive correlation between exposure to online hate and withdrawal motivations, and a negative (n-shaped) correlation with bystander reactions. (shrink)