You, good person, might grow up being bullied by other kids without understanding why. Being attacked without provocation, suffering psychological, emotional and even physical abuse. Perhaps even worse, you may even experience pharmaceutical or psychiatric abuse, even coming from the very family that should be supporting you.
Just imagine that these people are not naturally bad! They are extremely traumatized big kids, with personalities built on top of trauma. While you had your first 5 years of peace and health, their first 5 years were abuse, abandonment and/or violence to varying degrees.
That's what their personality was based on. They are cruel because they never had good examples nor do they know the benefits of being kind. It's not like they know how to look for what's missing in them either, when they don't even know it even exists.
Expecting this from these people is like intentionally looking for something without knowing what that something is - it's not possible. It is necessary to have an idea of what is missing in order to be able to fill it. Until then, this empty space will be filled with the wrong pieces, after all, decisions still need to be made.