[Belegorn]

The sacrifices you mention seem to me to be part of the last word in these chapters. Elendil and Gil-galad took out Sauron at the expense of their own lives, but Isildur kept the Ring and he died. The army of Elves and Men led by Maia took out Melkor, but the gift to the Edain not only uplifted the race, but brought with it its own problems. In the end Númenor became like a place where most of the Men were on roid-rage. I use steroids here because they were basically super-men even at the end of the 3rd Age. And at the end of the 3rd Age even though Sauron is destroyed and Frodo broken, the result is that Elves become ever more distant, so distant that they take up mostly at the abode for the immortal.