We need a bit of rationality here:

You are very right. A kid (or anyone?) with a gun is likely not going to end well. This is a truth of human nature.

But here is another truth of human nature: "If someone is not going to right a wrong, then I will"

Many in this country see a store looted by a crowd of 70 people, and the police cannot do anything about it. They WILL support an ever increasing degree of vigilantism. This is also a truth of human nature.

I am not passing judgement on either fact, except to notice that they are facts, and we must not ignore them.

The vigilante and the looter share a common belief that the police cannot handle the situation... and they are both right. the outcome is predictable and tragic.