Grey morality is nice for stories. It categorically does not exist in real life. The people you meet on a daily basis are not "morally gray". They're generally decent but flawed individuals, or they're just straight up selfish greedy callous bastards. You never encounter someone who straddles the line between "good" and "evil". The idea that there are people who do bad things for good reasons or good things for bad reasons has been sensationalized by media when the truth is most people are never put in situations where we're required to do either.

When people act with cruelty or malice, sorry to say, there often isn't a deeper reason for it. The bully picking on you at school doesn't have a secret traumatic backstory, it just makes him feel big and powerful picking on someone with less power to fight back, and he has a compulsive need to feel big and powerful. Could there possibly be a psychological reason for the for that that ties back to his home life, possibly, are you obligated to give a shit, absolutely not. And that is the underlying psychological failing of every evil bastard that has ever existed, from the schoolyard bully robbing you for fun to the Internet gangstalker doxxing some woman to your landlord destroying your life over six hundred dollars to the autocratic dictator committing a genocide. The main fundamental difference between all of these people is only how much power they have, and directly how how much damage they can cause. It's still the same mental deficiency at the end of the day. It's the difference between a stick of dynamite and a nuke. Explosions are explosions.