I think you do me an injustice, and needlessly so.

The US is not 'just one country' with the same ideals and attitudes everywhere. We are 50 states, and while there is an overall American culture, each state or even city area has its own local culture, ideals, politics, etc.
I live in a 'blue state' (IE Democrat-majority, Democrats are generally an anti-gun party). There's not a big gun culture here. There are not people with 10 gallon hats and a 6-shooter on their hip riding around in a giant pickup truck with a gun rack. My state has more gun control laws than most in the union.
When I grew up we had no guns or interest in guns. During my whole childhood the only exposure to guns I had was once at summer camp there was an activity shooting .22LR rifles (small caliber), lying down, at targets. And once on vacation we went to a shooting range that was part of a resort.

If we'd had this conversation 10 or 12 years ago, I'd have been mostly on your side. I recognized the 2nd Amendment was a thing that existed, but I saw no reason anybody needed an 'assault rifle', I thought gun free zones were a pretty good way to improve safety, and overall a lot of 'gun culture' seemed like needless penis extension.

It was actually one conversation that kicked off a change in my position. An old friend of mine and I were getting lunch together. This guy has always been very Republican (pro-gun/conservative party), owns several guns, goes hunting, etc- but we have a lot of mutual respect despite differing worldviews on many subjects. Anyway, as we finished lunch he mentions that he's going to buy an AR-15 rifle and would I like to come along? I made a dumb joke like 'damn man, I didn't realize it was that small, I'm sorry dude'. He just laughed and said 'You know my deer hunting rifle, the one you said you have no problem with civilians owning? Well it's actually a lot MORE powerful than an AR-15.' I started to argue but he said 'look, nothing I say is going to convince you. So just Google it when you get home, okay?'.
I KNEW he was wrong- a 'military weapon of war' would definitely be more powerful than a stupid wood stock hunting rifle like Elmer Fudd would carry. Surely the military wouldn't be carrying weapons inferior to those of random civilian hunters, right?

So I went home and Googled it. And I found he was right- his .30-06 hunting rifle has SIGNIFICANTLY more muzzle energy than the .223 AR-15 he was planning to buy. The hunting rifle was larger and heavier and in almost every way, more powerful.
I'm usually not wrong about technical things. So I was curious what else I was wrong about on the subject, turned out it was a lot. Not about policy or position, but about provable technical things of how guns work and how deadly they are and whatnot.
So I decided the best course of action was to basically forget everything I thought I knew, and start fresh. That kicked off a good 3-4 week deep dive on the subject, reading articles, watching YouTubes, doing research on both sides of the issue.

This brought about a few basic conclusions. The biggest is that most of the politicians who talk about guns appear to know little or nothing about guns, as many of their gun control arguments are easily disproved on basis of fact. And many of the laws they promote do nothing to regulate the actual lethality of guns, but rather try to describe 'scary looking guns' and ban those. For example, my own state's laws regulate rifles that have ergonomic features like a pistol grip or collapsible stock that have NO bearing on the rifle's lethality.

I then started doing research into use of force, defensive situations, etc. And that brought a very sobering realization- I lived in a bubble. Violence is not a part of my life (and I prefer it that way). My area is quite safe. But that doesn't mean I am immune to violent people- and there ARE people out there who ARE violent. Not many near me, but they exist.
And I'd say I've done more research than most into what happens in a fight. I've seen a lot of videos of defensive situations- robberies, fistfights, assaults, kidnapping, and straight up attempted murder. I've seen what happens when people get shot (you won't find it on YouTube). And I've seen how easy it is to seriously harm a human. We live safe lives in civilized society, but on the scale of the world, our bodies are pretty fragile and it doesn't take much to seriously damage them.

And that's why I say thought experiment for how to kill someone from 100' away. It's why I say that if someone wants to kill people, they will, gun or not. It's why I reject the logic that removing guns will save lives, because I recognize that gun regulations affect the law-abiding more than the criminals who are doing the most harm.

Point is-- I have done the thought experiment, a few different ways.

Do I want guns in vending machines? No. Is the absolute ideal to have everybody armed? No, the ideal is where nobody needs to be armed. But absent that perfect future, I think civilian armament as a deterrence to criminals works.