who many claim to be instilled with a strong sense of justice

They think justice is them (and people they like) winning. That’s what they believe. Values and morals are justifications for what they do, not reasons to do things.

That’s why they will never understand when you try to explain how they are not actually following their values, or heros, or religion. Their main idea is that they are correct and right. It’s not a complicated position but it’s very human.

If you don’t think like that, congratulations. You’re a better person. But that doesn’t mean you’ll be able to convince them that they’re wrong.