E.g. What is the expected effect on existential risk of donating to one of GiveWell's top charities?
I've asked myself this question several times over the last few years, but I've never put a lot of thought into it. I've always just assumed that at the very least it would not increase existential risk.
Have any analyses been done on this?
I believe there's an important case where this does actually matter.
Suppose there's a fundraising charity F which raises money for charities X and G. Charity X is an x-risk charity, and F raises money for it at a 2:1 ratio. Charity G is a global poverty charity, and F raises money for it at a 10:1 ratio. If you care more about x-risk than global poverty and believe charity G decreases x-risk, or only increases x-risk by a tiny amount, then you should give to F instead of X. But if G increases x-risk by more than 20% as much as X decreases it, then giving to F is actually net negative and you should give to X instead.
I don't believe 20% is implausibly high. This only requires that ending global poverty increases x-risk by about 0.01% and charity G is reasonably effective. (I did some Fermi calculations to justify this but they're pretty complicated so I'll leave them out.)