There are many candidate cause factors for the supposed decline ot the middle class to which you referred;
The primary one is the widespread decline of manufacturing and basic materials production (steel, aluminum, etc.) that started a few decades ago and which has eliminated large numbers of highly paid (and mostly unionized) jobs. The drivers here are competition from rising economies in Asia, primarily China. They are growing their wealth in the same way we did in the 19th century, exploiting competitive advantages associated with abundant relatively cheap labor anjd highly permissive environkmental regulation. I guess you could say that capitalism is the problem here in that, while China had a socialist economy it offered no competition at alll, and its people lived in abject socialist poverty. . It was only when they adopted capitalism that they began to accumulate some wealth and become themselves a capable economic competitor.
Meanwhile we are gradually paralyzing ourselves with increasingly restrictive environmental and labor regulations which have further reduced our competitiveness in these areas. For those who have not developed the skills required in our growing service economy this can be a painful situation.
I think the key point here is that capitalism is the real source of the needed solution, not the problem. We're facing increased economic competition precisely because other countries are casting off the chains of authoritarian socialism and planned economies in an effort to really create better living conditions for their citizens.
I don't expect Rex to allow this reality to intrude on his sophomoric delusions.