Violence runs the world and it always has. Peace is imposed from the point of a sword. Those without power or the inclination to fight are forever the victims of those who have them. Manners are a product of consequences.
And no, I'm not saying the world
should be that way or that it should be even more violent than it is, hail caesar etc etc. I'm just saying, what we have now is a system predicated upon violence at almost every level. That is what civilization is. You force people to be nice and if they aren't nice then you inflict violence upon them. We do it with prison and fines now, but the threat is always there. Resist and be beaten. Shut up, hands behind your back or eat this taser.
Without guns, the citizenry will have to accept whatever those above them dictate. At least if they own guns, citizens do have the option, however unwise, of responding "lol no" when told to do something heinous.
"But the military has tanks/jets/nukes."
None of which they can really use on their own populace without destroying their society. In America, we've seen about the limits of how much weaponry cops can bring to bear on their own citizens. I've yet to witness a swat team launch a fucking missile into some dude's house.
Or roll a tank over a crowd.
Those with power in America are very afraid of gun-owning citizens. Not so much because of the paltry power of those firearms, but because of what they represent. A body of people who can decide "hey, fuck this social contract, we're getting robbed" and violently rebel against it. Disarmed, the populace can only whine to the courts impotently when they are wronged.
Not to say that I want a Wild West scenario, just that the presence of all those guns is like a nuclear deterrent which the mega-rich and super-powerful must always remain in fear of. It reminds them they are as mortal as the next person and they could lose their lives if they get up to TOO much bullshit.