So is a ballistic missile. Should citizens be allowed to own those? If not, why? And who and what determines where the line is?
when the 2nd Amendment was written, private citizens owned cannons and warships, the same weapons that the government had.
Putting a limitation on what private citizens can have, so that the government has a monopoly on force, to use AGAINST its citizens, is exactly what the 2nd amendment was written for. Not for hunting.
The fact that Joe Biden argues that private citizens can't fight the US government in a state of tyranny because the US government has tanks and missiles and jets.. is kinda precisely why the amendment is needed. That the government would consider using such weaponry against its own people, is why you don't want a government having a monopoly on force.
That said such a thing generally acts as a deterrent, if your populace is CAPABLE of mounting a revolution against the government and overthrowing it, that deters the government from creating a state of tyranny that'd warrant such a revolution.
In the same vein of thinking, why do we have a nuclear arsenal? It's to deter the Russians, Chinese, and other nuclear powers from using their nuclear weapons on us, not that we plan to use ours in the first place. Otherwise the weapons are essentially useless for all parties involved. None of them can really use them because of the retaliation that'd happen would destroy them.
But no country will ever again unilaterally disarm themselves if they are a nuclear weapon state. Ukraine did in the early 1990's for security guarantees from the US, Great Britain, France, and Russia. All agreed that if Ukraine dismantled its 5000 ICBM's, that they'd all enforce Ukraine's territorial sovereignty.
Now look at Ukraine.
You think Ukraine would be in this situation now if they had 5000 nuclear warheads aimed at Russia?
Now, I suppose there is a line in that private citizens should not own nuclear weapons, mainly because safely storing them is difficult and costly...
but.. if a private citizen could afford something like tanks, warships, artillery, fighter jets, etc.. and someone would sell such things to them, or they make them themselves.. I wouldn't particularly have a problem with that provided they pass background checks and the tax stamps to possess such things. Private citizens do legally own grenade launchers, tanks, etc. Those aren't being used in crimes, because the people who have those kinds of things have been vetted, and aren't likely to use such things for violence.
Limiting weapons because you think a person is likely to use them for violence is a bad mindset to have in the first place. If I think a person is likely to commit violence against others, I don't want them owning a bbgun, I'm not going to tell them "well we won't let you have an AR-15 because you can kill MORE people, but here, have a 6 shot revolver"
It's either I trust them with machine guns and tanks, or I don't trust them with a pointy stick.
Not an in between.