People Make Suboptimal Decisions about Existential Risks

How should people allocate resources to maximize the probability that humanity survives a set of existential risks? We derive the optimal solution to this problem and use this solution to evaluate the decisions that people make when presented with this challenge. Our participants (total $N$=2,072) are appropriately sensitive to how responsive a risk is to investment, but are conservative in their decisions and do not allocate enough resources to risks with lower probability of survival. This pattern persists even with alternative framings that emphasize survival probabilities. Our results highlight a systematic flaw in people's intuitions about how to respond to existential risks.