This is as ridiculous as ‘guns keep us free’ and insurrectionist dogma.
You can’t compare the United States with European democracies – primarily because the United States isn’t a democracy; the people don’t decide national policy, there is no majority rule, there are no referenda.
Unlike the UK and Iceland, the United States is a far more violent society, where violence is accepted as a legitimate means of conflict resolution.
Unlike the UK and Iceland, the United States has no universal healthcare – particularly with regard to mental healthcare.
Indeed, the lack of gun crime and violence in countries such as the UK and Iceland has far more to do with comprehensive public policy and governance than firearm regulatory measures.