Kid stuff is kid stuff, adult stuff is different. That 9th grader had almost certainly never tortured someone with a car battery. Same with the muggers - who's to say that they're sane in the least? What if they're really strung-out and have knives, now you're going to the hospital.
When I tell people there's usually someone who tells me I should have fought back, or whatever. And I went through relief, anger, fear it would happen again and the thirst for revenge afterwards, replaying the situation and second-guessing myself, wondering if I should have fought back or done something differently.
But it's not worth the risk. My friend works in public housing in the area, and said the guy was probably a local gang member. These guys fight and carry knives from when they're children. I've never been in a real fight and I have a desk job - odds are that I would have ended up in hospital.
So I handed over the 40 pounds cash I had in my wallet, and he bailed.
A random encounter like this is a totally different situation to a bully at school, where you mostly know who you're dealing with. There's a couple of times I now realise I probably should have stood up for myself at school, but being mugged on the street is not the time to start learning to fight.
In my view, it's never worth risking your life to protect your belongings. Be like Roger Sterling in Mad Men and give up your money & your jewelry.
Shooting an attacker is safer for you. It is usually far more expensive, though -- maybe 1-5k in legal costs even if it doesn't get much followup (and if it goes to trial, could be over 100k), potential civil suits, and of course the cost of firearms and training to even have the choice.
I would definitely toss a $500 wallet and run if it were at the time a safer choice, even with a firearm. But, I would have no problem killing to defend my life, either.
I was speaking mainly to a situation where you'd be inciting some sort of a fight or a struggle with someone crazy enough to attempt a mugging. In this case, I still stand by my feeling that you're better off complying.
If you're able, by all means, protect yourself. You'll find no objections from me there.
Now, a certain feeling of invincibility may be priceless to some people, but they're far less invincible than they think - if you go around expecting violence then it's probably more likely to happen to you. Not to mention that, statistically, you're shortening your lifetime more by owning a gun (I like guns but don't own one) than you're extending it by the small chance that someone's coming for your life and you actually see them coming.
Carrying a concealed weapon (where legal) has a lower benefit than carrying a cellphone and first aid/trauma kit (which I also carry, and will try to get to EMT-I certification again, if not paramedic), but I still think it's a net improvement in your personal safety, assuming you're trained and competent.
The biggest disadvantage is that in some states you can't go into a restaurant where alcohol is served (even if you're going for a meal and don't drink), and of course the fashion compromise of a 1-4 pound hunk of metal/plastic/wood.
I think most gun owners disbelieve "invincibility" even more than non-gun owners when it comes to guns -- handguns especially are fairly non-lethal (at 3', I'd rather have a knife), and give an advantage to he who initiates violence. I'd be very happy to trade a firearm for a Dune-style shield or something.
I think another factor is that a responsible gun owner who is carrying is probably more likely to avoid places where an incident might happen -- aside from bars, I'd also be a lot more likely to be less confrontational in traffic or other situations if I realized there was a potential it could escalate to shooting. I've never been involved in any kind of scuffle or anything while carrying a firearm, and while I actively avoid "bad areas" to the extent possible no matter what, it's another factor. Although I am willing to stop to render aid to stranded motorists when armed, whereas unless it's a very clearcut situation, just drive on (and optionally call 911) otherwise.
once somebody is threatening you with violence, you don't get to count on anything. especially if you act like an easy target.