Chick flick in New York

Since people have good reason to believe that the auto factories of Detroit and the steel mills of Pittsburgh could not be re-opened by a society running on Libertarian principles, although a socialist state could do that if it put its mind to it, and they perhaps lack the imagination to see how AnCap would suddenly make job opportunities of other kinds spring up all over, thus solving the big problems of economic inequality... they will fear scenarios like that.

The auto factories of Detroit were overrun by feral animals on two legs - but only after a government was elected that did not allow people to defend themselves against feral animals on two legs.

The bad guys in Detroit prey on each other, therefore lack cohesion.   Good guys can cohere.  Thus, absent government in New York each bad guy would individually face a large bunch of good guys united.  Of course, in practice, the good guys united would be mostly white vigilantes, and the individual black bad guy would usually be black, which is a form of violence that was forbidden because it would have the appearance of racism, would look very like the KKK.

So I think that not only could anarchy get Detroit back in order, it took massive government intervention to reduce it to a jungle overrun by dangerous wild animals.

Some tiny fraction of humanity, as we know, does go around freely killing, raping, and pillaging unless met by force.

is true, it's also true that the fraction of humanity that can live without a group is much, much tinier. 

And in order to run them out of the group, you have to threaten those people with deadly violence – tell them to get the hell out of Dodge by noon or die.

And if they don't get the hell out of Dodge, then you have to kill them.

I expect I would be one of the heroes,

Don't we all.