>>94219371 Hippie Stan's original plan was to have Charles be legitimately evil, and Magneto as a misunderstood freedom fight. Because at that point in time, School/Establishement = Baaaad & Rioters = Gooood. Obviously that didn't catch on, and Magneto just became the antagonist.
As for why? He's a legitimate speciesist, he always fucks people over and is a hypocrite. You can find "good" traits in him, and he did grow as a character, but he always ends up reverting to his villainous ways. He's a tad better than Doom, but he's an elitist, so...
