We built the largest middle class the world has ever known post WWII. A lot was luck. The only undamaged infrastructure after the war. We got to provide the materials to rebuild after the war. Plenty of jobs. They in turn spend the money. Created more jobs. We have been living off that kick start since.
Without a strong middle class we are done as a country. Thats the danger for us. If the income inequality keeps whacking the middle class it will lead to slow decline but an ending that works out well for no one.