NOBODY should have a gun or other weapons.
Well, firstly, you should define weapon. As I understand it, a weapon is anything that can hurt anyone, as simple as that. So, if your statement were truth, mankind hasn´t existed because everything in our environment can be used as a weapon, even some parts of our body. For example, if you hit somebody with your head, you might hurt him badly, even you could kill him (ask Zidedine Zidane, the football player, about using the head as a weapon). Or knifes have to be eliminated because anyone can be stabbed, so we should learn to eat with our hands to avoid further aggression with them.
But if you´re talking about firepower (I mean pistol, rifles, etc) that´s another thing. To me, ban guns is an useless measure because we are the most self-destructed being living in this world. I reckon if guns didn´t exist, We would have invented another thing to replace it. I think ideally, everybody who wish to carry a gun have the right to get one, only if he fullfill the laws existing. But, sadly our current laws about it are so lax that every crazy person can get one without any problem, so we must change the laws first before let anyone to carry guns.
To sum up, I think everybody can carry a gun only if laws are changed.