There's a broad category of social turmoil that is life threatening but not quite the magnitude of "professional military starts attacking citizens." Say bands of political extremists of whatever flavor start attacking towns, or other smaller-scale (in comparison to outright civil war) acts of violence erupt. I don't dispute your anecdotes from the Balkans, but using it as blanket proof to say that firearms won't ever be of benefit in times of civil unrest is not effective.

You are right, but that's not really an apocalypse but a localised civil war. Admittedly, it would be good to be prepared for that, but I think leaving the area altogether would be a more optimal solution than grabbing weapons.

Sure, but leaving the area means abandoning a place of shelter, community, and potentially a decent chunk of supplies. I agree, plenty of disasters wouldn't warrant use of firearms, but having them and not needing them is considerably better than needing them and not having them. Seems like one is strictly better than the other. I suppose possession of unnecessary firarms could risk having them stolen or otherwise ending up in the hands of people doing harm - but seeing as 30-40% of US households possess firearms, this is a moot point.