That is all part of natural selection. Humans are pack animals, and the instincts for competition are both within the pack heiarchy as well as with other tribes and species for resources and shelter.
Maga is it's own pack as a doomsday political cult. They've made other Americans their enemies due to trump's rhetoric and Fox News' propaganda painting that picture. So maga is only following their base animal instincts by following their pack leader and refusing any evidence to the contrary.
Humans have the potential for development in critical thinking and challenging the pack rhetoric, but you have to actually decide to challenge it and think critically. It's more difficult than just going along with whatever information you were inundated with throughout your life.
Maga are in 2 main camps. Either mentally incapable or they gave up their ability to judge this situation critically. They receive information that validates all of their built in prejudices and insecurities on a daily basis and will not listen to reason otherwise. That's why they invent falsehoods and stories to explain away any situation like the assassinations in Minnesota. Just like what happens in cults and religions.
IMO the only way to alter it is to cut off that daily flow of propaganda and lies. Social media would have to be wiped out of anything political in nature. Political TV and media would have to be banned. It would require mass censorship to have a chance of de-escalating this powder keg built on lies and prejudice.
And that's the saddest part for me. I want to believe in freedom of speech. I want to believe people are evolved enough to properly discern bullshit from truth over time and adjust accordingly. Some people are, but a very large percentage of people are not. I'm afraid with the constant nature of social media free flowing bullshit in Western democracies that it'll be the censorship states like China that pull ahead in the coming decades as they regulate out much of that noise. And it sucks.