Why can political conversations get so divisive and toxic?

Most people cannot discuss the [i]issues[/i]. That's where it should stay, but it rarely does. Ad hominem attacks should never enter the picture. Strangely, though, an attack on someone's favorite political hero appears to tap into an egotistical/narcissistic side. I don't understand it, but time and time again, there are people affixing the suffix "tard" during said ad hominem attacks, and that's where you lose me. It's sick, often blind, cultish hero worship, often with a weak argument or no basis in reality. People literally invent virtues that their hero does not possess, and I think it has to do with the ego( I VOTED FOR HIM/HER, THEREFORE THEY ARE UNASSAILABLE).

I'm happy to talk to anyone, regardless of party, who isn't an argument baiter or takes 100% of their input from media talking points. Things aren't black and white. Really, though, I'd rather talk about music.