Let's make this one a double, barkeep.
...because the right of some scumbag to rob a grocery store and terrorize the customers and employees therein is more sacrosanct than the right of one of those customers to prevent him from doing so.
Violent criminals at the mercy of decent, law-abiding citizens: One of the fringe benefits of living in a free society where people have the right to defend themselves.
Decent, law-abiding citizens at the mercy of violent criminals: One of the costs of living in an authoritarian police state where only lawmakers and lawbreakers are afforded that privilege.
Night, meet day.