Decades of "the ends justify the means" gritty antihero's, doing what "needs" to be done.
Honestly its surprising how many people have beliefs they think are evil but just they alone can bear the moral cost to support it. Its why it doesn't matter to some about Trumps crimes against democracy or rapes, they are just making "enlightened" real politic game theory decisions in there heads instead of understanding the value of ethical and honarable institutions.
At least that's part of it. An over value of "accepting a little sin" to get what they want instead of accepting the nuance and boring reality of what it actually takes to build a better world.