Because you can't get rid of guns completely. For one, the security forces of those in power will have them and second, those who intend to do bad things to people will have them.
Once the technology exists and is available to the public, one can no longer stop its proliferation.
Or you just ban it completely for everything but hunting and regulate that strictly (ofc with exceptions for police and military). This is the way gun laws work in most European countries and most of them are indeed very save places to live in.
Your point here is a typical American one and just not any good. Guns in self defense rarely help anyone and do way more harm when random idiots who suddenly feel a need to kill someone finds themselfs already with a gun in their hand. Not to say that it's impossible to get your hands on a gun in (for example) Sweden but the price and complications that ce with it do stop a lot of people from doing stupid things.
Well yes, but Americans have that unpleasant thing called ACAB that likely prevents them from accepting any attempt at removing their perceived self-defense against the abuse committed by authorities.
ACAB is a global fact, not unique to America. It's also a fact largely recognised by the same kinds of people who are opposed to the free flow of guns. The kinds of people who think guns should be unrestricted are also the kinds who, by and large, are supportive of police and believe police are on their side.