That’s an argument but I disagree that the person themselves should be in charge of the decision of whether or not they have the qualifications to control a deadly weapon. Have a certification test and a license you need to renew every once in a while, or heck just restrict private gun ownership to military veterans and people who have been trained in the public sector, and you minimize the number of people with guns and thus gun deaths (and thus overall deaths because they don’t transfer to other methods 1:1) while not relying on police.
Or take guns away from the police too, there are countries that do that.