I don't think he thought along lines of good or bad or evil at all. He noticed that he had a knack for firing people up, first in conversations, then in speeches, etc. Like any power hungry ego maniac he simply kept doing it and kept succeeding through an endless string of insanely unlikely circumstances. I'd bet a good 30% of the population would follow the exact same path, given those circumstances / opportunities.

He wanted infinite power, because he was likely infinitely afraid of the world. He never once thought about what's good or bad. He only thought about how to get more power and how to maintain it. The inevitable conclusion to that game is always world domination with a bunch of genocide mixed in. You can see the patterns arising everywhere at the moment.