Or the risks of hospital-acquired infection (maybe his girlfriend considered that). What about effects like if it aches for years afterwards but won't kill him; at what level of ache would that turn from "reminder that I did a good thing" to "damnit"?
Hand transplants are a thing - would he give up his non-dominant hand to someone who lost both of theirs in an accident?
Eye transplants aren't a thing, but if they were, would he give up one to a blind person?
If it was really easy to see the damage (hand) and lose an obvious piece of functionality (eye) it would be much harder to argue with numbers "studies show that most people who lose a hand survive more than 7 years". Would he lose an eye, a hand, a kidney, a lung, a lower leg, a foot of intestine, a chunk of liver, a section of skin, a few litres of blood, if it did more good to someone else than to him?
> "Indeed, OP tries to present a bunch of arithmetic to justify their decision, but admits that it ultimately rested on an emotional gut feeling: "It starts with wanting, just once, do a good thing that will make people like you more instead of less.""
The Last Psychiatrist wrote that you shouldn't need validation from other people, shouldn't want it, and if you do want it - fix that. Doing it hoping you gain some indelible "society values me" token to carry around with you forever so you can use it as a trump card and people will like you more, feeling like you've never done anything good and that you need to to be likeable, doesn't sound much like "altruism: Unselfish concern for the welfare of others; selflessness.", does it?