I seriously think you are missing the point here. 

We can argue about the great utility of cars another time. I just picked that metric out of the blue because data is easy to find. On that note, they (cars) actually do a hell of a lot more harm than good, are far deadlier than a gun, and take far more from our economy and quality of life than they add, but that's not really the point of this discussion. 

The point is, everyone is in a tizzy about school shootings. This is more and more being used as an argument for more and more guns. School shootings are indeed something we should pay attention to, but they are actually extremely rare events. More people die from falling coconuts, mosquitos, choking, tripping, champagne corks, and yes, even cows, than from school shootings each year. 

I think back of the envelope comparisons to provide perspective can be valuable to gauge how severe a problem actually is. That's all I'm doing here.