Many years ago, I encountered an elderly widow who lived alone in a modest home. One morning her neighbor noticed that her back porch light was on past the time she usually turned it off and went to check. When he saw the back door ajar, he called her niece and the police.
They finally found the woman at the bottom of a closet, alive but badly beaten. A pile of bedding was thrown on top of her and a dresser pulled in front of the closet door so it could not be opened from inside.
She lived but with severe brain damage, could not speak, did not recognize her niece, etc.
This little old lady was perfectly harmless, just trying to live out the rest of her life in peace. She had nothing really worth stealing.
When you really grasp that there are people, to use the term loosely, who are capable of brutalizing the fragile and helpless such as the elderly and babies and young children, well, then, you don't put a lot of faith and trust in "human nature."