This is why I wrote the Buffyverse crossover where he meets a vampire instead of an angel on the bridge, gets turned, loses his pesky conscience, and no longer cares if he's made the world better or not!

(I'm not saying that's an *ideal* solution. But it's a solution that applied to his actual problems! :P And less glibly I do think a lot of times the only possible, if super unsatisfying, answer is stop worrying about ideal solutions and long-distance theoretical consequences for other people, just play the cards you're dealt.)

(Not that I'm any good at *taking* that advice; I've never ended up on a bridge over whether the world-as-a-whole would be better without me in it, but I've too often ended up wishing that I was a person who could.)