When someone who owns and knows how to handle a gun lets the criminal know that they have a gun, the criminal most often shows his chicken little guy side and runs. And the few times he doesn't run... well that is the 10% mentioned that the gun is fired.
But in almost 100% of the cases... the property owner and their loved ones are safe. Yes, they still have to deal with the mental aspect of someone invading their personal space... but they are alive.
In cases where the property owner or their loved ones are injured or killed... you can flip the numbers and over 905 of them were defenseless when confronting a violent criminal.
A good guy with a gun is the best defese against a bad guy with one... period!