And the logic that "people are going to get them anyway" is really awful. People make and buy meth anyway, people steal anyway, people rape and murder anyway, might as well make it all legal right?
You tell me my logic is awful. Then you make my point for me. Need I say more?
Like you said, all those illegal things, people do them anyway.
Stealing is morally and fundamentally wrong. You could always ask for help/money, or just get a job.
I would never do meth myself. I'm of the opinion of "to each his own" however. If you wanna rot your teeth, kill exorbitant amounts of brain tissue, and destroy your throat and lungs, by all means, go ahead. There's safer ways to get the type of effect as I understand it, but by all means, it's your body, feel free. Just don't hurt anyone else.
Rape is, in a strange way, analogous to stealing (although it down right disgusts me that anyone would do this). You're taking something without permission. Like I said before, you could always ask.
Murder is the act of taking another human life, and by definition, murder is "killing someone without just cause," in the law's eyes, just cause for killing is if your life is threatened by the person you killed. They still might throw you behind bars. But I digress.
Guns however, are a tool. None of these other things mentioned are analogous to guns. Guns may be a tool of death, but they are a tool nonetheless. Most of the aforementioned are actions, not tools. If someone is threatening my life with a gun, I would feel much safer if I had a gun to defend myself, or if someone nearby had a gun and the gumption to defend me. People will think twice about using a gun against someone if they know there person can just turn around and do the same back. It's called a level playing ground.