When was the last time you actually saw someone grab a gun and go be a "first responder" to a crime? You haven't.
You seem to believe this doesn't happen. It does. I know because I was the guy with a gun.
In August 1998 a young man was getting beaten to death in my apartment's parking lot. (Whether it was their intent to kill him, I don't know. What I do know is that beating someone with a tire iron is lethal force.) One of my neighbors called 911. I went out with a 12-gauge loaded with deer slug and suggested they leave him alone. They stopped beating him. When the deputy sheriff arrived a few minutes later this young man was in bad shape, but was still alive. He's alive because I had a shotgun.
In 2006 a younger friend of mine who had been the victim of a violent rape ten years before received word that her attacker was being released from prison. The prison psychologist contacted my friend to let her know this rapist was still obsessed with her. He had a three-day window between the time he was released and the time he registered his new domicile with a local county sheriff -- three days during which my friend was intensely vulnerable. The police said they'd send a car past her place twice each shift. That was no comfort at all. But when several of her (armed and trained) friends took shifts in her home with a shotgun, she was able to rest well. (And each day she woke up to a hearty plate of eggs, bacon, toast, and a cup of hot Jamaican Blue Mountain.)
A couple of years ago a friend of mine had to testify at a trial and was afraid to walk to the courthouse for fear the defendant's friends would waylay her. She shared her fears with me. I shrugged, holstered a Glock, and walked her to the courthouse. I didn't go inside (since that would've been a violation of the law), but I handed her off to a sheriff's deputy who took her the rest of the way to the courtroom. She felt safe the entire way.
You seem to believe guns are the problem. Guns are not the problem. Guns in the hands of the irresponsible, the untrained, and the immature... now there's a problem for you, an enormous one, and one I don't have a good answer for.
But a rifle, a shotgun, or a handgun, in the hands of a responsible, mature individual who's been trained in their use and the legal statutes pertaining to violence... we genuinely are the first responders the original poster talked about. And our business is violence *prevention*, not violence. Our presence deters violence. I like that, I like that a lot.
I've got no desire to shoot anyone. Killing is a messy, disgusting business and I recommend everyone avoid it. A gunshot will involve years of nightmares, torturous soul-searching, civil lawsuits, the deceased's friends and family wanting vengeance, and every other damned thing imaginable... and that's for a 100% justified kill. There is literally no upside in shooting someone.
But preventing bad things from happening to people? I have to say... that's kind of cool. I like that. A lot.