TBH my sense is that GiveWell is just being polite.
A perhaps more realistic motivation is that admitting animal suffering into GiveWell’s models would implicitly force them to specify moral weights for animals (versus humans), and there is no way to do that without inviting huge controversy leaving at least some groups very upset. Much easier to say “sorry, not our wheelhouse” and effectively set animal weights to zero.
FWIW I agree with this decision (of GiveWell’s).
Personally I don’t think Sam Altman is motivated by money. He just wants to be the one to build it.
I sense that Elon Musk and Dorio Amodei’s motivations are more complex than “motivated by money”, but I can imagine that the actual dollar amounts are more important to them than to Sma.