either I can affect things like AI risk [...] In which case I’m willing to give to those causes today
It could be that you expect you can affect important things today, but that your actions won’t have a perpetually compounding effect, so in the long run you can do better by investing to give later.
Or I have little confidence in my judgment on these future matters, in which case I should help people living today and again likely invest nothing.
Similarly, in this case it could be that you expect to do better by investing your wealth to eventually help the future, and that by the time the future comes, you (or your descendants) will know how to help the world at that time.
I do broadly agree that it only makes sense to invest for the long term if you make certain assumptions.
I sort of agree but not entirely:
It could be that you expect you can affect important things today, but that your actions won’t have a perpetually compounding effect, so in the long run you can do better by investing to give later.
Similarly, in this case it could be that you expect to do better by investing your wealth to eventually help the future, and that by the time the future comes, you (or your descendants) will know how to help the world at that time.
I do broadly agree that it only makes sense to invest for the long term if you make certain assumptions.