American media is full with the Rittenhouse case. I can find Hungarian articles too, but different priorities. I don't want to dwell on the issue, my main thoughts actually are related to the On Killing.
He very effectively killed two of his assailants, and injured a third one. If the On Killing is right, that is not an easy feat. Either you have to be that type of person, who disregards human life, or there has to be a number of circumstances and conditions that helps to overcome of the inherent block most people have.
I read/see enough to know he was training with weapons, not just target practice, because in our time and age weapon handling is preparing for scenarios when you have to defend yourself, use your weapon. And those irl scenarios rarely resemble to target practice. Training can overcome to the block. He also had first hand experience of what the "protesters" did. The situation was essentially a riot, with brutality committed against people, and vandalism against property (both private and state). Kyle could have considered his actions justified, he was there to provide safety. The participants frequently behaved like mindless animals. This could allow him to deny their humanity. He was with others, older role models, both providing example to follow, and expectations raised towards him to do what they thought is their duty (among them, his duty).
So I recognize a number of conditions Grossman listed. Might be more.
Despite these enabling factors, a normal human bean will suffer trauma, due to his acts, and have to deal with what he did.
Ofc, I can't tell of his psychological profile, is he a kind of psychopath or not, so won't guess about that.
From yesterday's Tucker Carlson Tonight here's a part where he talks about his dreams.
The first video is ofc, the shooting that happened in Kenosha.