Bryan Caplan argues against the "corrupted by power" idea with an alternative view: they were corrupt from the start, which is why they were willing to go to such extremes to attain power.

Around the time I stopped believing in God and objective morality I came around to Stirners' view: such values are "geists" haunting the mind, often distracting us from factual truths. Just as I stopped reading fiction for reasons of epistemic hygiene, I decided that chucking morality would serve a similar purpose. I certainly wouldn't trust myself to selectively filter any factual information. How can the uninformed know what to be uninformed about?