Spot on. The world is full of violent amateurs. (I think Murphy said something to this effect). Unless you're going force-on-force with a squad of enemy infantry, your opponent is just a two-bit thug. One who almost certainly spends less time at the range, cleaning his weapon, or otherwise preparing for his life being on the line. He's resorted to violence because life's other options have proven too taxing, and his application of violence, while enthusiastic, will also be amateurish.
The one time in my life an enemy got a completely free shot at me, he missed a <150m shot at the unguarded back of a stationary target. Likely because his sights were closer to his bellybutton than his eyes when he pulled the trigger.
That's inexcusably incompetent for an allegedly trained anti-crusader combatant, rolling the dice against Team Infidel, but hardly uncommon.
Even with training and experience, most thugs are idiots. That's why they're thugs. Their inability to make sound decisions puts them at a strong disadvantage against an aggressive opponent that acts rationally. Grandma doesn't have to be hard as woodpecker lips, 300+ on her PT test, and at the range every Sunday after church to put steel on a half-wit criminal. She just needs a gun where she can get at it, and the sense to do it at the right time.
On a macro scale, that's what society needs; brave amateurs who will fight back. On a micro scale, sure, you-the-individual want to be as ready as possible to defend your own life, and the life of others. But be real. Most Americans aren't going to spring for a few weeks at Blackwater learning combat rifle and pistol, though. We should be happy if most able bodied Americans just owned a gun, were willing to use it, and practiced adequate weapons handling and safety.
But lucky for you...