A couple key passages:
The US elites, similarly, took the smooth functioning of the political-economic system for granted. The only problem, as they saw it, was that they weren’t being adequately compensated for their efforts. Feelings of dissatisfaction ran high during the Bear Market of 1973—82, when capital returns took a particular beating. The high inflation of that decade ate into inherited wealth. A fortune of $2 billion in 1982 was a third smaller, when expressed in inflation-adjusted dollars, than $1 billion in 1962, and only a sixth of $1 billion in 1912. All these factors contributed to the reversal of the late 1970s.
Three years ago I published a short article in the science journal Nature. I pointed out that several leading indicators of political instability look set to peak around 2020. In other words, we are rapidly approaching a historical cusp, at which the US will be particularly vulnerable to violent upheaval. This prediction is not a ‘prophecy’. I don’t believe that disaster is pre-ordained, no matter what we do. On the contrary, if we understand the causes, we have a chance to prevent it from happening. But the first thing we will have to do is reverse the trend of ever-growing inequality.
And finally this one:
How does growing economic inequality lead to political instability? Partly this correlation reflects a direct, causal connection. High inequality is corrosive of social cooperation and willingness to compromise, and waning cooperation means more discord and political infighting. Perhaps more important, economic inequality is also a symptom of deeper social changes, which have gone largely unnoticed.