If everybody had guns then everybody could defend themselves against maniacs and psychopaths that want to cause harm to yourself or other people. Pretty simple concept is it not? Some killer with mental illness and violence would be put down in the act.
Sure, just like if all countries had nukes whenever a rogue country decided to blow up another country everyone else could blow up the rogue country. So pretty simple, the world is a better place if everyone has nukes.
If guns are hard to get access to then why make it easy by letting everyone have the? Again this doesnt really count for america because everyone and their dog has a gun.