In my world, a civilized person is one who upholds peaceable society, and a barbarian is one who uses force to upend that society. They're not hordes, but they are barbarians.
If you encounter a failing justice system and your response isn't "let's fix the causes" but instead "thankfully I believe in convenient self-service executions", you aren't upholding peaceable society, and I suspect that a peaceable society isn't what you'd prefer.
Consider too that there are many documented cases of the authorities being incompetent to or unwilling to stop a threat, most recently in Bondi Beach, but also in Uvalde. Maybe they’re just not coming to save you?