I'm not American, I'm originally European, and I currently live in a country where guns are banned. Technically you can get guns here, but it's a hard process that may take a decade and results in you losing the right of privacy in your own home, so my reply isn't from the perspective of an American.

The purpose of guns from an American perspective is to guarantee that the final political power always rests with the ordinary citizen, not with the government.

Here in Japan I don't have to fear some criminal is going to shoot me (nor stab me, or throw acid at me, or anything of the sort), violent crimes do happen of course, but they are incredibly rare.

I still believe, however that American gun culture is something every country should aspire to emulate; not because it makes daily life safer in the short term, but because it makes long-term political survival possible.

The Japanese state is polite, efficient [though too bureaucratic], and overwhelmingly non-violent, but it is also a black-box sovereign. If tomorrow a Diet majority decided to impose an unjust law the citizen has no last-resort leverage.

In the United States the Second Amendment is a constitutional declaration that legitimacy flows upward from the people, not downward from the crown, the party or the bureaucracy. The rifle in the closet says: “We can still say no, even if every other mechanism has failed.”

That veto power is deliberately expensive to exercise, nobody wants war, but the existence of the veto changes the calculus of every actor inside the system. A would-be autocrat must ask: "Will my police, my judges, my neighbours pull the trigger for me, or will they refuse and, worse, shoot back?" The uncertainty alone keeps the ceiling lower than it otherwise would be.

The system is not perfect of course, but I'd rather have it than not.