And that's the point! Armed revolution is
really bad, and massive inequality is one piece in a puzzle that can lead to it. It seems really odd to me to shrug this off as at least part of the answer to the original question of why inequality is bad.
We have been more or less immune to this in the US for a long time because of our large and strong middle class that has had way too much to lose. But that's the same middle class that the elites are eroding by short-sightedly capturing an ever larger portion of the modern economy's output.