Forgive my ignorance on the topic of firearm ownership, but isn't deterrence part of the point of owning a gun? From what I know about deterrence theory in warfare, clearly communicating your capability to back up your threats to your opponent is usually necessary for success. Doesn't it follow that a gun is most useful for keeping people out of your house if they know you have it?
I think it makes less sense to be stealing a gun from an armed man than to be stealing more profitable computers, televisions, and cameras from an unarmed man. But then again, we are talking about criminals here