If you have a gun, you have to decide to escalate really quickly, then you need to shoot to kill very quickly. Mostly thieves use guns to deter resistance. Not always, but there's usually little reason to risk murder for cash or a car. I don't carry a gun, because I have no reason to get in a gunfight.
Statistically I know that being armed increases the chances of being shot but I would like to know how the odds change if a person is professionally trained and maintains their skills.
Someone close to me recently managed to break up a large crime ring in the area after they tracked their phone down to the thieves' apartment. They didn't just find her backpack, they found the backpacks of tens of other victims. What is the chance most robbers only hit once? (As a coincidence, I'm reading A Clockwork Orange right now, who knows how many devotchkas that book's fictitious hero scarred)
But, don't get me wrong, I am not against gun ownership, or even concealed firearms. I just have no interest in having one for the perfect situation, considering that most situations will be far from perfect. My father was a hunter, and a few in my family are gun enthusiasts. I've shot all sorts of guns from assault rifles to 9mm. The ones that left the biggest impression were a 12 gauge slug, a .44 magnum, and a SKS modified to auto with a banana clip. I just don't want to be involved in gunfire. I suppose if I was in law enforcement, or a veteran that saw combat, I might feel comfortable carrying. I doubt any training matches that kind of casual readiness. Clockwork Orange is an incredible book. I read it for the first time about two years ago.
Unfortunately, I'm too young and lacking on money and time to buy a weapon and get trained, it is on my to-do list...but chances are it'll only happen after I leave the high-crime area I'm currently living in.