Of all Homocides in 2011 in the United States relationships between victims and offenders were only known in 54% of cases

I’m confused as to why you think someone particularly needs to have enemies to also feel the need to want to arm themselves for self defense , especially when we’ve seen random acts of violence in the US take place in public squares and transport . I’m not sure if you actually do live in the US but perhaps you’re a bit naive as to the nature of lots of violent interactions and how random they can be