Allowing lethal stand-your-ground style self-defense and vigilantism are both pathways to violent anarchy and chaos. They are the antithesis of government.
Standing up to thugs and bullies and thieves seems to be sort of ingrained into the human psyche. Knowing when you're outgunned and need to back down is also a useful survival instinct. We are practically hard-wired to defend ourselves under duress. And sometimes can't be held responsible for our actions.
Vigilanism on the other hand is like Neighborhood Watch where volunteers keep an eye on the streets at night because police patrols are few and far between. Back when I had teevee I remember Sherriff Gunsmoke used to just deputized Festus and Gomez when the LEO force was shorthanded. It's the most honorable thing a fellow can do...stepping up and protecting property and rights when they are threatened.
Pathways to chaos and violence? Antithesis to government? Seems both are simply phenomena that happen on a personal level and at a societal level.