John Johnston has a look
My personal take on it is that yes! a lot of people with little to no training were able to prevail were number one reason, they prevailed?, they had a gun, the vast majority of criminals are those looking for an opportunity, they are not looking for a fight.. When suddenly confronted by an armed victim, they realize they have more pressing manners elsewhere. Which in studies are considered "Defensive Gun Use" such as Gary Kleck's studies, we are using guns 3 million times a year to stop what may have become a violent crime, in over *90% of the cases shots are not fired, in around 8% shots were fired, and nothing was hit., of course at the point the would-be criminal now knows the intended victim, is not really a victim at all, has a gun, and beats feet, in most cases.
In the 2006 FBI study of assaults on Police Officers, they found : 40% of the criminal attackers received formal firearms training, over 80% regularly practiced with firearms (averaging 23 practice sessions a year), more than 40% had at least one gunfight experience, and 25% had been involved in more than 5 gunfights. Of course in most law enforcement shootings the officer is in the process, of arresting someone who does not want to go to jail, and they fight to avoid going, and the dynamics of most LE shooting are different than those of civilians.
So when people tell me they hope they get lucky if they get in a gunfight, I tell them first off being in a gunfight is not being lucky, and if luck is involved, it is the attacker does not have the will to press on in the faced of armed resistance.
Yes in most cases the citizen with little to no training will prevail, if they have a gun, and have the wits to produce the gun, the criminal will seek greener pastures
For me I don't want the least going into a fight, I want the most, to insure my winning the fight.
In a lifetime, people will spend thousands and thousands of dollars on insurance, and the majority will never have their house burn down, or be involved in a car wreck, but balk at the thought of getting defensive training, spending a few hundred a year preparing themselves for something most pray never happens.
I'd never had fun writing those checks to those insurance companies, but I have had a lot of fun in defensive shooting classes, that help insure my safety.
But the choice is your's if you feel what you have in training, mindset, equipment, etc are enough, then I wish you the best, but if you have doubt consider taking a course once a year.