Can treating a workplace bully with kindness really change their behavior, or does it only work if they're misunderstood rather than truly malicious?

Why do old people who are seriously ill (like cancer, ect.) and suffer hardship not give up their life? I mean they aren't happy and healthy at all, also they have already lived long lives, and their illness cause trouble to their family.
How does your dual personality of being both ruthless and empathetic coexist, and how do you balance the two?