I thought the NPCs especially, selfish at first, then I remembered it was Yuna's own decision to give her life for a few years of peace. She believed her life was worth a few years' comfort to the rest of the world, and that good would come of it.

However, her beliefs turn out to be misguided when we find out that Yevon is perpetuating the whole thing (making the world believe the only way to stop Sin is to send summoners to their deaths), whcih is sad.