In America, it was not "1990" – try 1980, with the election of Ronald Reagan, followed by the GOP being all but subsumed by Koch brothers, one of whom was the VP candidate on the libertarian ticket, running against Reagan.

We've seen the shrinking of the middle class since at least Reagan. His policies gutted middle class stability. But, you can also see the beginnings of the rightwing hollowing out the middle class at least as far back as Nixon's policies. Since Nixon, the GOP has skewed further and further right.

However, the real devastation of the middle class came at the hands of Tea Party politics which took over the GOP completely in 2010. Those Tea Party politicians were just the Koch brothers libertarian ideologues cloaking themselves in the hollowed out skin of what was once the Party of Lincoln. Then, the GOP skewed even further right into to downright extremism under the aegis of Donald Trump. They became openly hostile to the ideals of democracy itself.