All you'll do it redirect targets, not prevent it.
My point. Right here. Spelt out.
You CAN"T stop it, but you can redirect it or limit it. That's the goal. If you believe ridding a country of guns reduces violence, it doesn't. It REDIRECTS the weaponry of choice, or redirects how one goes about it. As far as the walrus statement, if you truly believe a hard target has just the same odds as getting hit as a soft target, it is delusional. The problems with organized terrorism and your run-of-the-mill domestic terrorist equal the same ideology, but with different means to obtain it. Organized terrorism can produce larger weaponry (usually illegal), but your domestic terrorist will just change routes. Like stated, banning guns won't stop an anger, mentally ill person from making a shit ton of molotavs and just tossing them at people. It wouldn't stop someone from driving a truck full of explosives into a building. It wouldn't stop someone from obtaining a knife. Running a parade over with your car/truck. It does not stop evil actions. Equating domestic terrorist to organized terrorist does equate to they will always find a way to do damage. Banning guns won't solve anything.
All that security is reactive, if someone walks in with a rifle the best it can do is limit the issue, not prevent it. Unless you get very very lucky, an armed teacher can respond after the first shot is fired. Which you know, if you consider 15-20 kids getting shot instead of 30+ a good deal, may be worth it...but that's a pretty shit metric for a solution.
This is why guns are needed. Exactly what you stated. An armed teacher can only respond after the first shot is fired. How much longer would someone wait for a police officer? An SRO at the school might have to wait for backup before reacting. Teachers can provide that initial backup since, at least around here, they are provided the immediate response training necessary. A long, buckled down gun fight? Probably not, but that gives time for SWAT and police to respond. A quick response is better than a prolonged one. If you were at the mall, and someone set the mall on fire. Nothing could stop the initial fire from happening, because someone in love with arson wants to start a fire. Does that mean you wait for the fire department to arrive, or does the mall have sprinklers to try and tackle the fire initially? Fire extinguishers to tackle it initially? You can't put out a fire that isn't there yet, but you can change how you react. Faster reaction = better. If that is a shit metric to follow in a world where violence won't ever go away, I'll take my shit metric every time.
The reason why an AR-15 isn't traditional used as a hunting rifle is because it DOESN'T have the stopping power needed for bigger game. The irrational fear of it being the most dangerous weaponry available is unrealistic. It does, however, provide therapy. Myself included. Going to the range and having to calm down, take the time to watch your breathe, make far off shots, that is relaxing. Customizing a gun that is just yours is relaxing. It feels accomplished and prideful to look at something you made. This is that culture you speak of. It isn't a culture of fantasting about a gun to go out and shoot people. Anyone with that mentality shouldn't have a gun to begin with. The "man-card" idea is the same as cars. Guys love cars. We argue over brands and models. Ford vs Chevy, Camaro vs Mustang, etc, etc. We argue over Colt vs Sig. 1911 vs any other handgun. M4 vs M16. It's not a culture designed to be violent. It is a culture designed for our interests and hobbies. My girlfriend's brother and my girlfriend have been trying to get me and a few buddies into air soft. Haven't tried it yet. Interested to see how therapeutic that can be. I just bought a rifle the other day, though apparently I need a mask and stuff. lol.