According to Thomas Piketty and others, the only political
circumstance that ever led to a thriving middle class was around 35 years of war, economic turmoil, revolution and general crisis starting in or before 1914, plus the 20-30 years of recovery that followed it -- partly because the wealth (and therefore unearned income) of the rich was largely destroyed (so, arguably
NOT a good thing, overall). Since then inequality has been stable or increasing. Here is the wealth inequality of the USA, which was little affected by WW1 (aside from a recession just after it; Western Europe went from a greater extreme of inequality (60-ish% to the top 1%) to even less than the USA, but I could not quickly find the charts):
If we are (un)lucky, Trump may be a new crisis like this.
I have also heard that one reason why Latin America is less equal than Western Europe is that they were little affected by the wars of the 20th century -- but I am not an expert.
I know that this is not really fair as an argument, but I find it interesting that the country where most of the talk about "liberty" and private property seems to come from, the USA, seems rather low-trust compared to, say, the Nordic countries or Germany. I wonder how that contributes to the popularity of right-wing "libertarianism" over there.