if bulma bought a gun for defense for fear of neighbourhood robberies, and then i robbed him during the two week wait period (if he did it through "legal" means), then he says "hey don't rob me", and i says "i had to rob you, because you were getting a gun and i feared for my life."
I wouldn't buy a gun.
Guns are not actually much better than other weapons. It's hype.
The actual popularity of guns for years was not their power (arrows have physics behind it, as the entire force generated by the length of the shaft means penetrating power enough that an expert can pierce multiple layers of bulletproof glass). Kevlar is also no defense against certain heads of arrow. The only disadvantage is loading time for any one who isn't really skilled.
And it actually takes 20 seconds to set up a gun, as Mythbusters found out by two separate "knife to a gunfight" tests. Having any weapon handy, even a walking stick, has enough time to either disarm a robber or kill them. The key is not being intimidated. They're a joke.
Do you know the actual reason pistols achieved popularity? It wasn't its power. And even if it does fire a faster projectile, the lack of mass means it's basically a pea shooter. Further, a skilled archer can load and fire a bow about as fast as a gun. It was two reasons:
1. Lack of need for training (to get bows to full effectiveness, you need a great deal of strength and skill)
2. They're loud, meaning they can be used as startling weapons.
Now, a shotgun, at close range, I might buy that weapon. The spread of multiple pellets has good stopping power. Maybe a machine gun that's preloaded. But many revolvers are basically the same model as 100 years ago. And pistols do occasionally jam up when refilling the clip, as I found from the firing range.
I also like swords a fair amount. In the amount of time to shoot me with a gun (remember 20 seconds to draw, cock, aim, and fire), I could simply give you a nice slash across the chest. Even with the first three taken care of, I probably have about three seconds if you miss, and I'm gonna swing anyway, cuz momentum will probably finish you off too.
So yeah, (1) you're as much an idiot as I thought, and (2) you don't know me at all.
If you tried to rob me, fearing for your life doesn't make sense as a justification. Any court would understand that most states have laws about carrying guns outside openly (meaning they stay at home for most legal gun owners), whereas castle doctrine is a thing. If you break in and threaten me with a weapon, fighting back even with lethal force is a reasonable option. You being afraid is a bad excuse, because most people (not me) would buy a gun out of fear of robbers, not the other way around.
Relating this back to Russia, just as I have completely my own approach to self-defense, Russia doesn't need to follow America's playbook on defending their country. But if you told me that you were going to convince my next door neighbor to join a gang (the IRL equivalent of NATO), most people would buy a gun as soon as they heard about this. I'd go to a blacksmith, cuz that's me.