The Probability of Existential Risks

In his book, the precipice, toby ord takes a basian approach to quatifying existential risks. He adds up the chance of variousexistential catastrophes befalling us in the next 100 is and reaches a rough overall estimate that the chance of an existential catastrophe befalling humanity in the next100 years is one in six. Question for you: Should we use base rates like that to estimate the probability of existential risks and help prioritize which ones we address? R says absolutely not. In some cases, e, the probabilities er can be known because they are the result of good explanations. So there is no way of using basianer reasoning to address them.