When talking about guns, debates seem to be of the standard script. Anti gun folks will point out shootings and crime. Pro gun folks will counter with statistical probabilities and examples of states. All of this is in the attempt to justify being able to own guns. But all this is missing the core issue.
From an excellent blog post from Reason.com:
It’s a question that’s become a bit of a mantra for would-be restricters of personal armaments who insist on knowing what possible justification gun owners could have for possessing semi-automatic rifles that have pistol grips, or for purchasing magazines that hold more than ten seven rounds.
But really, that’s all irrelevant. Because in free societies, you don’t have to justify owning things…
As I look around my office, I see a lot of stuff I don’t need… My ability to acquire pets and stuff that I want without having to justify the acquisitions is an expression of my personal freedom. If I had to go, Stetson Stratoliner in hand, to some puffed-up bureaucrat to beg permission to purchase the boxed set of Firefly DVDs or a mutt rescue dog, I would very obviously be living in a state of severely constrained liberty.
The appropriate answer to “Who the hell needs … ?” is “hey, if you don’t want one, don’t buy it.” The right to own stuff without an explanation is the right to be free.
When someone asks: “Why would you ever possibly need [insert item of choice]?” The appropriate answer is “Because I want one.” We should not have to justify our wants to some bureaucrat. We should be able to own what we want precisely because we live in a free society.
reality is not optional 
Of course the answer is: “Should you be able to own an A-bomb?” To which my reply is: “Nah. They’re too heavy. Hard to store. They make too big a mess.”
Maybe the real answer is: “Should A-bombs exist?” Well, they do.
With your logic, you could argue that the government should be able to ban pressure cookers. In the real world, in order to justify banning something, you need much more than a simple utilitarian calculation. For your consideration:
http://spot.colorado.edu/~huemer/guncontrol.htm
I also wonder how, as technology gives people instant access to cheap uncontrollable guns through 3d printers, your views will change. How will you cope with having no control. Get with the 21st century. https://christopherfisher.wordpress.com/2013/05/07/making-the-state-irrelevant/
But then one might want to buy some atomic bombs and hire some people who know how to launch it, to “just for fun” destroy a country.