Why do you think that many people believe strangers commit most violence acts?

Because they have no reference to said person, they see them as someone who can harm them without thinking twice, however, it has already been proven that more people are close to who are more likely to harm you.    

Money, greed, jealousy are the three main reasons 4 most violent acts.

Explanation:

Money-maybe they are poor, though that they need more than what they have or someone owes them and never paid them back

Greed-very selfish person that thanks what they have makes them a better person. So they would kill for what the other has.

Jealousy-this goes for men and women, relationships. One could look at the other in a way their partner disagrees. Causing a violent act. Or, this is mostly women they become jealous a friend or someone else and makes me feel less powerful. What causes anger anger turns into violence.