This needs context, because if you read it after watching the movies, you'll completely misunderstand. This is from when Magneto started redeeming himself and giving up his murderous ways. He later states that the only reason he joined this particular conspiracy was so he could face the Red Skull. This speech didn't slam Magneto and his cause, if anything it made his resolution to reform stronger. As for the moral high ground, he later left the Skull to die, buried in a pit with a big jug of water.

Apparently you either die a villain, or you live long enough to see yourself become the hero. IMHO, this was one of Magneto's better moments.

"He who fights monsters should see to it that he himself does not become a monster. And if you gaze for long into an abyss, the abyss gazes also into you."

-- Friedrich Nietzsche, Beyond Good and Evil