It is easy to blame Trump's incompetence, but I think there are 2 more important reasons to consider:

1. Industrialization of Asia and factory automation

2. The rise of efficient agriculture in 3rd world countries and the consolidation of American farms into big companies that also increased productivity through automation.

True, Trump was incompetent because his policies only worsened a bad situation. But he alone isn't the problem.

And there isn't too much the US government can do to revert this economic decline. The solution, if there is one, has to come from innovation from the private economy.

Without a big change, the U.S. will only become more socially and politically unstable and more dangerous for itself and the world.