In the US, since the very beginning, not just the last 35 years. Most of the Founding Fathers were extremely wealthy. James Madison, who wrote most of the Constitution, opined that the purpose of government is to protect the minority of the opulent from the majority and that’s why you have aberrations like the Electoral College. They are not bugs in the system, they are working precisely as designed.
On the other hand, the premise of the article is demonstrably false. Sweden has far higher wealth inequality than the US, as the majority of its wealth is concentrated in a handful of families like the Nobels or Wallenbergs, but it exhibits none of the pathologies the US does, starting with a complete absence of noblesse oblige. That seems to be a specific failing of Anglo-Saxon countries, and even there developed recently, since the 80s or so (Reagan, but he was probably more symptom than cause), rejoining your 35 year figure. It would be interesting to find out what specific sociological trigger among the American wealthy led to this ruinous course.
