I would argue that wealth in the last thirty years was driven by two primary methods:

1.) Automating basic and well known tasks using computers.

2.) Outsourcing not easily automatable tasks to foreign counties and importing cheap labor. Manufacturing, software engineering etc.

Things like getting wealthy in real estate and investments were off shoots of the above.

I would argue that the two above have reached their capacity to be of benefit to average Americans. Further development of the two will continue to destroy the middle class and the cultural fabric of America. People are increasingly aware of this, hence the tense political climate in this country