Why is Sauron made out to be evil in Lord of the Rings?

I don't see why everyone makes him out to be such a bad guy, he just led a revolt of an underprivileged, mistreated group of minorities against a tyrannical, racist, spiteful oppressor using the only non segregated army in the world at the time. I feel like he should be a hero for getting land and food for orcs, uruk hai, goblins and trolls and their probably starving children. Even if he did use violent means to get this, looking at it from his perspective makes his cause seem quite just