Sometimes people say stuff like ”EAs started working on AI x-risk because even a 0.001% chance of extinction is worse than [existing harm to present humans]”. But this isn’t true. EAs started investigating a wide range of possible x-risks, and focused solely on those with +0.5% chance, like nuclear war, (engineered-)pandemics, and AI x-risk. They didn’t focus on asteroid strikes. There are two reasons not to focus on very rare extinction events. Firstly, this triages with other x-risk categories. Secondly, even if all the x-risk categories had turned out to be 0.001% (so triaging isn’t a cost), you still shouldn’t have worked to reduce this likelihood. At best, your work reduces x-risk by 0.001%. But your activities could inadvertently increase that x-risk category to 0.1%. For example, the technology required to reduce asteroid strikes from 0.001% to 0.0001% (asteroid tracking, asteroid deflection) could be misused as a doomsday device, increasing asteroid strikes to 0.1%+. You might still do preliminary research in calculating the likelihood of different x-risks, because that could switch your overall judgment, but even that research might be ill-advised. For example, you shouldn’t do gain-of-function research to help you estimate the feasibility of an engineered pandemic. Overall, EAs started working on AI x-risk because they initially thought that the likelihood was +1%