For example, Donald Trump lies repeatedly. We may come to see a president as liar as normal. He also makes bombastic statements about nuclear weapons, for instance, which can then be seen as somehow normal. In other words, his behavior as president, with all those who defend his behavior in the administration, becomes a norm. post 
We have to contest it, because it is malignant normality. For the contributors to this book, this means striving to be witnessing professionals, confronting the malignancy and making it known.
Power breeds an intensification of all this because the power can never be absolute power — to some extent it’s stymied — but the isolation while in power becomes even more dangerous. Think of it as a vicious circle. The power intensifies these tendencies and the tendencies become more dangerous because of the power.
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I am reminded of “The Art of the Deal” which made America see Trump as a charmer with an unfailing knack for business. Tony Schwartz helped create that myth—and regrets it. This story, from before the election, helped me understand a lot of what was going on. post
See also Eichmann in Jerusalem: A Report on the Banality of Evil. wikipedia