It is a tragedy when a construction worker falls to his death while working on a skyscraper. It has happened before, and will happen again. Yet, no one says we should stop building skyscrapers.
I look at it this way. Crime is a profession, too, and it has risks. One of the risks is death. Certainly, the death of even a criminal is a tragedy. Hell, the misspent life is a tragedy. If gun ownership increases the risk for the criminal, so be it. Then a would-be crook can look at the risk before entering the profession. Maybe the risk will be too high. Good!
There is no shortage of construction workers, even though they know the risk of their profession. The only difference between the crook and the construction worker is that society is better off if we minimize the risk to the worker (hence safety standards), but we maximize the risk to the criminal (armed citizens).
Have you ever had a person point a gun at you? I have, in a street stick up. It is a very, very scary feeling. Believe me. You’re paralyzed. You can't attack and you can't out run a bullet. You just hope and pray that the guy is not going to pull the trigger for the hell of it. I think every criminal should have to face that feeling during the commission of a crime. Like they say in the old cowboy movies, "One false move and your dead."
And even as a tragedy, the death of a criminal may have a benefit to society. Since most criminals are repeat offenders, and often become more dangerous as their careers advances, there is something to be said for the potential of precluding future crimes.
I really do not see where the right to carry and conceal makes us all vigilantes. This is about personal protection, not community-based volunteer crime fighters. Police are rarely at the scene of a crime as it is unfolding. We are. That makes a gun the real "first responder."