I guess those kids that open fire in a school are taught how to handle a gun too.
Having guns doesn't reduce the criminality rates, like you said and i said, criminals doesn't follow the law. And there will always be criminals, it doesn't matter if you think that you're safer owning a gun, you're not.
Wearing a gun is also illegal in many places, and since most crimes take place out of your house, how does a gun helps you there? (let's remember that criminals do not obey the law, so they carry weapons in the street anyway).
(old US news) A guy that bought a gun legally, and then someday he decided to take the gun to the office and open fire there.
(repeatedly US news) A children stole a gun from his parents, he takes the gun to his school and open fire.
(yet another US news) A children kill himself when he was playing with a gun.
Endless stories.....none of them had happened in Mexico, why?, because guns are illegal.
No single person should own a gun, only military, police and such should have them, that's what they are for, to protect you, if your neighborhood is unsafe and somebody can break into your house even if you get to notice him....then that's another issue in itself (consider to move on).