They think that by no one being able to get guns that magically people will stop killing people. They'll find other ways to do so. Some are also not masculine and thus do not realize the need to defend ones self. Some (including the non masculine I just mentioned) trust the police and government way too much. They think the government will always be protecting them and on their/our side and there's always the risk of the government going corrupt. The solution? Keep the populous armed, keep parents competent in their ability to raise kids and people need to leave general problem solving skills along with having a good sense of purpose in life