Defending yourself isn't being ing Rambo. Don't be a pussy. You cower and get shot in the head like all those people or you fight back. I would fight back. I might die. I might die either way. I am a military vet, I don't give a what he says. The cop in Florida who did nothing was criticized for not doing anything, but he wasn't in harms way yet somehow he's supposed to walk in and engage the guy with the rifle. However someone in the thick of it needs to cower and die because well, don't want to risk getting killed. You won't limit events because you won't know the ones you've prevented. Limiting casualties is the only solution and even then, I am the primary casualty I am trying to prevent.
Don't bifurcate the situation to never armed vs always armed. If you want to protect yourself and you are concerned about this kind of thing, you'll do what's required. Otherwise you'll hope you don't become one of the unlucky ones and experience an event, and hope someone does something about it.
The reason police stations and gun shows aren't attacked is because the shooter wants max casualties with minimum personal risk. Every time another gun free zone is created where people are packed in like sardines, it's feeding time for the crazies. Churches, schools, theaters, bars, stores (not all stores are gun free zones, but the odds are most people in one aren't carrying and I've not seen any armed protection for anything but the money drop).
It's odd, we put 2 cops at banks but none where our most precious resources are. It makes you wonder if human life is really that important. That's why I said protect yourself first. If you don't want to, that's your choice. You won't talk me into being a victim.