I want you to consider a scenario: Imagine that every individual had the means to protect themselves from any physical attack, kidnapping and therefore coercion. This seems, in theory, to be the ideal for a libertarian. No one would be able to harm you and you also could harm no other individual; no violent crime of any nature could occur.
Mutually Assured Destruction doesn't apply to regular people with handguns.
Cite: every street gang ever