Someone feeling threatened or alarmed because they see a gun doesn't mean the owner is being threatening. I might even take pleasure out of people being scared of me carrying a gun because I think they're a bunch of wimps, but me lawfully carrying a gun isn't a threat of violence unless I point it at someone or make a verbal threat to shoot someone.
Ok.
Lets put it simply.
How do YOU tell the person who is about to take that gun off their back and start shooting everyone from the person who is enjoying making other people uncomfortable, or the person that is so **** scared of "the bad people" that they need the reassurance of openly carrying a weapon that is pretty much useless at quickly protecting themselves, or in an enclosed area?
"Long arms" are pretty much pointless in most self protection situations as they take too much time to pull out, and aim, and are hard to use in enclosed areas (which is the reason the military tends to use shorter versions of the weapons, or hand guns for things like house clearance and base or ship protection), yet large obvious guns are the go to for the idiots that feel they must demonstrate how much of an "alpha" they are by showing off their toy.
If you're "sensible" as a gun owner, and open/concealed carry you're going to be constantly nervous, on edge and evaluating the threats whenever you see anyone else with a gun, or anything that might hide one - because they're a potential high risk, if you're not then you're going to get caught by surprise...
The non carrying people who might be nervous are likely to be so because they have no idea of the people who are carrying weapons intent, state of mind (are they going to see a "threat" that isn't there and react), or simple competence (are they going accidentally shoot me because they've got poor trigger discipline and can't remember to clear their weapon or keep their finger clear of the trigger...).
The argument that having a gun makes you able to protect yourself has always been a bit of a nonsense in many of the situations where it's claimed it will "save yor", for example having a gun on you doesn't help if someone pulls theirs first or you've got your hands full, or you have to spend several second fumbling to get your gun from being "safe" to usable, having a huge honking gun on your back doesn't make you safer against someone who doesn't care if they die, it just means you're probably going to be the first person they shoot after they've killed the trained security guard/police officer next to you (and if they don't, when the police/swat teams arrive you're going to treated as a priority suspect and likely shot by them*)
Even Police and trained military personal have been killed despite being "on duty" armed and supposedly ready, because the shooter is someone they didn't spot, didn't assess as a threat, or was simply faster for whater reason (better training, better familiarity with the gun, no hesitation in pulling the trigger, or had a smaller gun that was simply easier to aim quickly).
The US is raising a whole generation (well two, probably coming up to three now) of people who are effectively low level PTSD from the school shooting drills, because they've had to spend large portions of their time in an environment that has taught them to be wary of loud noises and consider if they're going to have to sacrifice themselves or their friends when the shooting starts.
*Some of the popular holsters used by self proclaimed "alpha" "muh gun rites" idiots have a bad tendency to catch on the trigger of their guns, and some of the more popular handguns are designed in such a way that they don't have a separate safety so when the gun is pulled, or even just jostled the holster can be enough to
