> Yeah, A Farewell to Alms makes a pretty convincing argument that 1945 to 1971 was an anomaly. Ever since the advent of agriculture, income inequality has been on the rise. The Belle Epoch in France was the peak of that - then revolutions, World Wars, and Socialism happened. Once that civil unrest stopped, the trend continued back up.
Its worth noting that large scale disasters (of all sorts) were always great equalizers, a countervailing force to rising inequality. In general, the more you had to lose, the more you lost.
We've been getting better at preventing or coping with a lot of these things like plagues, famines, and so on, but we've become even better at insulating accumulated wealth from being destroyed by them (including by financial crises), by privatizing gains and socializing losses.
I have a feeling that we've entered a new period of larger scale social unrest and natural disasters which may or may not significantly destroy and/or redistribute wealth to level the playing field again somewhat.
(We might have recently passed Belle Epoch-levels of inequality - not sure this is an accomplishment we should brag about)