I'd have to say that the "why" is explained in the Bible. From Genesis 3, to Romans 1, 3, 5, Psalm 14, and throughout. Man, by nature, is evil. We are a fallen race, whose first parents were deceived by Satan - the god of this world who has blinded those that believe not. So man, without Christ, is governed by his lusts, pride, and ego. The ends justify the means. I am sure these people can rationalize whipping up hatred with the end being that they gain more power to enable them to do "good stuff". We certainly should call them out on these points, and oppose them, but we need to remember our battle isn't with them.
Ephesians 6:12-13
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
They are willfully blind IMO...and yes man's nature is bent on evil without Christ....but I have not seen it so paraded before us and that with pride and arrogance so blatantly. But then they "Do strut their evil before you" as is written. Which then makes me think..."when the wicked come to power men go into hiding".....I read a commentary on that...basically saying they cease activities of commerce, of works etc. and prosperity comes slowly to a hault.
Thank you for your post....And even if they do think the end justifies the means and excuses their actions in their own minds....I find it much hard to hope ...for them. And not sure I can anymore....not sure I want to.....