IMO very few people in this world know how to carry a gun and how to use it effectively. The obvious would be law enforcement officers, military combat veterans, and people who take the time and the initiative to get properly trained.
Only a tiny portion IMO get the training and experience necessary to defend themselves. Some people cannot afford that training or find a qualified instructor in their community.
Others think hitting a paper target is all they need to "be qualified." No paper target I've ever shot at has shot back, and there lies the rub.
That's why I think combat veterans, for the most part, have the entire scope of experience. Very few others do.
How many cops in an entire career have ever been in a gunfight? A tiny percentage, I would guess. Most NEVER.
Also, it is not a fact just found in movies. Every year gun owners are killed with their own guns.
Having the gun is the easy part.
Here is a quick example.
Several days ago, my neighbor asked me if he could borrow my truck to pick up some lumber.
Sure I said I'd get the keys. I handed him the keys and asked if he needed an extra hand. Nope just getting a few sheets of plywood.
He took the keys, walked over to the truck, and climbed in. He sat there for a few seconds, got out, a started walking back to me. I said it's a big gray key, thinking that was the problem. He had the keys had access to the truck has a driver's license.... so what was the problem? It was a 4-speed standard transmission; he never learned how to drive a standard.