It was a light-bulb moment when I learned that in medieval warfare, battles were relatively rare, and the primary mechanism of military force was the siege: camp outside and block trade/supplies, until the enemy runs out of food and gives up. Even if one has overwhelming force, fighting is expensive and risky, whether for an army or an individual [0]. This pattern replicates throughout nature: many animals develop signals to proxy their fighting strength without having to fight, due to the risk it would incur (such as growling as a signal of chest cavity size).

It's perfectly cogent to own a gun, not with any intent to kill, but to establish a power dynamic, such that one could respond with deadly force if necessary [1]. This is how America projects its military power across the world, through 400+ bases and several aircraft super-carriers, with the majority of that force going unused. It's still a projection of power, and still subject to moral scrutiny; but having a military base parked outside Qatar, just in case, is not the same thing as "that military base is a tool for invading Qatar".

I get your core point; weapons being deadly is the whole point, and even weapons acquired purely for deterrence can lead to a positive feedback loop of escalation, resulting in violence that would not have occurred otherwise. And humans are not purely rational actors; there's a simple numbers game, where the more guns are in a populace, the deadlier a small number of maniacs or extremists are going to be. It's not a problem we should ignore, and it's frustrating that NRA hardliners seem to be fine with doing so.

I don't own a gun, and I'm in favor of something resembling "common sense gun control", as well as other harm reduction interventions (particularly universal mental health care); at the same time, I consider effective self-defense to be an inalienable human right (I don't declaw cats, either). But to say that guns exist only to kill is a little overly simplistic: to take another example, North Korea acquired nukes not to use them, but to dissuade the U.S. but ever thinking about instigating regime change. They know using them can only result in their immediate obliteration; yet owning them tilts the game-theoretic dynamic in their favor.

[0] Aircraft and drones somewhat change the dynamic on this, but we can consider those out of scope in a 2A debate.

[1] https://en.wikipedia.org/wiki/Credible_minimum_deterrence