Who does acts of aggression not thinking it is "self-defense"?

[Mr Khan]

I don't get why this case has gone to trial, unless Norwegian criminal law is different. This guy is clearly insane, so if anything this should just be a hearing at a mental asylum

Everything can be spun as self-defense of some sort or another. Preservation of our self-interest is the only reason we do anything (the key is that often what is good for the group is good for us too, so society actually functions, usually), so outside of clear insanity, being proactive in a negative way is usually couched in self-beneficial terms.