If we believe that people have a free will. We will fear them even when there is no need to fear them. Any person on the planet could at any moment choose to do something bad to you. Maybe it will be a parent, a sibling, your spouse, or a complete stranger who breaks into your house. Will they kill you? Will they torture you? You can’t know because if their choice is free from all constraint, prior causes, and even their personality, then NO ONE can be trusted.
Not only are you afraid of something happening to you at an unknown time, but you also know that you cannot call the police. They have guns and they might freely choose to shoot you. If you are religious, you might decide to pray to your god, but that does no good either. Even if your god exists, if god has a free will, he/she/it might send you to hell to punish you for some sin that you freely chose do to even if you can’t remember what it is! Even worse, God might choose to punish you for no reason at all. Remember, free will does not require a reason.
If there is anything that we should fear, it would be a world in which people had a free will. This is the number one reason why it must be explained that people don’t choose to do things without a reason. Yes, people are scary and often they do murder each other, but often there is a way of predicting who can be trusted and who cannot. How much you trust someone is determined from your past experiences with them. There is a reason that we fear some people more than others. This is why we must examine our own actions and feelings to look for clues about what caused us to be the way we are and why other people do what they do.