Government does harm simply by existing. A decrease in liberty is harm. In order to justify that harm, positive, measurable benefits must be shown overall, at a minimum, not just some hypothetical, pie-in-the-sky mythical possibility of benefit.
Liberals and Progressives are very good at constructing hypothetical situations that show the benefit of more and more government power. They are also pretty good at creating false data showing government benefits.
They are really good at ignoring real world harm caused by the government.
When someone has relatively little warning (days rather than months) of a threat, as with emerging stalkers and irate ex-boyfriends, that saving in time and money can save the life of an innocent person. Even if the stalker's intended victim does not choose to carry, the uncertainty arising from constitutional carry may save lives. I do not believe that the cultural phenomenon of "stalker" would have arisen in an area where concealed carry was pervasive.