If you listen to the conservative messages closely, most of them are crafted in a way that sounds positive, not evil. Then what’s evil and can’t be shown any other way gets framed as the necessary evil to make those positive messages come to be.

The left goes very similar route, speaking of equality, freedom, love, and then coming up with something like “the world would be a better place if rich feared for their lives”. Might be true, but it’s the necessary evil/angry pushback again.

So, it’s not that people on the right chose to be evil, they just grew with one set of convictions that portrays left as unwilling to see the truth or to accept the sacrifices necessary to make the place better overall (in their eyes). And, similarly, far left that wants to overthrow or radically change the system is seen by the right as a massive evil force willing to destroy the country that took centuries to build a system that led people to where they are now - in relative prosperity and peace.

That is not to say they are correct in their thinking - there are massive flaws in their logic - but when you’re committed to a certain worldview, it’s easy to ignore inconsistencies, blinded by the fear of other side destroying it all. This, unfortunately, is what left resorts to as well, while being objectively more true (as in scientifically backed), because in the crazy world of politics emotions go first and reason goes second. Most people never get to cautiously verify and scrutinize the talking points presented to them, after all.