In any situation where you're faced with someone who has a gun and is actively trying to kill you or others around you, it would be better for you to have a gun than not have a gun. If someone right now was trying to break into your house to kill you, everyone here would take a gun if offered. It's easy to sit and conjure up a worst case scenario and suggest people won't be trained to high enough standards to be effective, but ultimately that's compared to a zero chance of survival when you're unarmed and in imminent danger of being shot. You're arguing to deny a human being a basic fighting chance rather than being a sheep to the slaughter. In an ideal world no one in America would have a gun, no one would go into schools and start shooting kids, but currently that isn't the case and America will not take away everyone's guns anytime soon.