When people USED to get killed for looting, or for attempting to destroy someone's home or place of business, we decided, as a civilized society, that this wasn't a good way to do things. Not that it wasn't effective but it was too draconian. (Please remember that before we even had this level of society, this draconian one, things were even worse. Tribes fought tribes for land, murder was a part of life...etc etc....)
So, as several posters have already posted, we turned over some of our power to the "authorities" and we had police who handled that sort of thing with arrests and jail time and fines. And we had civilization. And we didn't have massive riots, cause the PENALTIES for such were jail time, court time, fines, etc.
But when the people who have our authority, refuse to use it when people are looting and attempting to destroy someone's home or place of business in the name of a protest, then we have every right to defend our selves and our property, and it is not the fault of the defender if one of the looters/rioters is killed. Particularly if the rioters/looters are armed with lethal force.
It is draconian. It is a bad trade; a life for items/property But it's not as bad as having civilization drop all the way back down to anarchy and small tribal warfare.
And if there is no penalty for looting, robbing, burning, destroying, than we aren't living in a "civilized" country/state. That is anarchy. That is warfare.
I say this in response to anyone who makes comments like "can't be killing someone over a bar of soap and cigarettes" and are using such comments to vilify people like Kyle Rittenhouse. The majority of people want civilization. They want the authorities to use their authority given to them by the citizens to protect them. But if the authorities aren't going to do that, the next best thing is for citizens to take matters into their own hands.