Well, we can start with you I guess.
Everything you post here is readable by everyone.
People who shouldn't have guns wave them around at somebody who cut them off,
Bigotry. Brandishing without justification is already illegal, regardless of the weapon.
or they wave them around and passersby,
Brandishing is already illegal.
or they themselves in the leg,
I assume you mean shoot themselves. If someone shoots themselves, they only have themselves to blame. It's no different than cutting yourself on a knife or getting into a car accident because you're a lousy driver.
or somebody else in the leg
If you shoot someone else in the leg, you are already held responsible. It's no different than if you run into 'em with a car because you're a lousy driver.
or they get drunk and shoot a family member, or neighbor, or themselves,
Same thing.
they let 9 year old girls fire a machine gun
They can't. Even if they COULD hold the gun, it would knock 'em flat. Who is letting 9 year old girls shoot machine guns?
and get killed when the girl loses control of the machine gun,
Examples of this happening?
or they walk into a school or place of business or go to Las Vegas and commit mass murder with guns,
Also pretty damn rare.
School shootings are going to take place regardless of gun laws. The favored weapon in school shootings seems to be a .22 pistol or rifle. No school shooting has ever lasted longer than 10 minutes before some good guy with a gun kills the bad guy with a gun or the shooter shoots himself. Schools themselves are actually to blame for this, by creating 'gun free' zones.
or because guns are so prolific in the streets they can be picked up by 14 year old gang members and used to kill other gang members and little kids who happen to playing outside.
Gangs will get guns regardless of any gun law.
What else ya' wanna know?
You spent quite bit of time pointing out examples of why people need guns.
To defend themselves from gangs that have guns. To defend themselves from mass murderers. To defend themselves from a drunk with a gun. To defend themselves from bad guys with guns.
Guns exist. They are fact of life. You have to deal with them. Your hoplophobia is not going to make it go away. The examples you point out are the rare cases of bad guys with guns.
You are surrounded by people carrying guns. They aren't shooting up schools, rock concerts, getting drunk and waving their gun around, They aren't shooting themselves or anyone else in the leg. They are carrying their guns precisely for the reasons you mentioned. If a bad guy with a gun shows up, a good guy with a gun can stop him.
Your argument is actually a fallacy, known as a compositional error fallacy. You are making this fallacy with people as the class. This has a name: bigotry.