From FEE.org:

By taking away our means of self-defense and refusing to provide a suitable substitute, gun-free zones violate our right to life.

Our right to defend ourselves isn’t a function of the risk of our being victimized. Rights are grounded in the dignity of the individual, not statistical averages. Self-defense is a liberty that I have by virtue of being a human being. I don’t lose that right just because the circumstances in which I will need to use it are statistically rare. Otherwise, this same argument could be used to rule out any kind of self-defense.