It's a common internet myth. Just like the one that you'll be the first one they take out. For all my time looking I've only found 2 instances of someone taking the gun. One was possibly a set up as the person was trying to get concealed carry laws passed in one state. His complaint was that if he could have concealed the gun it wouldn't have been stolen. The second happened within 24 hours of the guy purchasing a gun and might have been a false report while trying to avoid the straw purchase laws.(by reporting it stolen)
As for them shooting OCers I haven't seen one report of that.
Now, with cops that arrest violent criminals both happen too often. But we are under no obligation to try and arrest.
What some people have noticed is that suspicious characters seem to leave and look for easier prey. No sense in dying for some cash or a gun.
Which brings up one of the things we talk about and that is situational awareness. Col Jeff Cooper came up with the color code for this.
http://en.wikipedia.org/wiki/Jeff_Cooper
http://www.policeone.com/police-trainer ... awareness/
Biggest thing is to stay in yellow. (relaxed alert) White is where far too many people spend their time thinking they'll always be safe and don't pay attention to the world around them. Orange is after scanning and something seems off and you raise your awareness to this level and start planning action. Red is where you act. When first learning about this many end up in orange. This taxes your system and can't be maintained for long periods.
Once you get the hang of it you'll wonder how you spent so much of your life in white. Yellow is where you should be while awake. Never so engrossed in what you're doing that you're not paying attention to things around you. Matter of fact the only time I'm in white anymore is when I'm asleep. And except for when first practicing this I've only been in orange a few times for a short time.
Situational awareness if practiced all the time will keep anyone from getting close to your gun. Even if they get close you've already shifted to orange and are prepared for what might happen next.
"The human race divides politically into those who want people to be controlled and those who have no such desire." - Robert A. Heinlein
What a shame that we have the two major political parties that believe the former.