One partially correct answer is that your prosperity was taken by the very people who promised to ensure and enhance it. The decades from 1980 through 2008 were the age of neoliberalism — the ideology of the free market. Financial deregulation, tax cuts and a lax attitude toward consumer protection and antitrust were supposed to free the entrepreneurial potential of the American middle class. And to some degree it did — those decades saw plenty of wealth creation, and the U.S. economy performed a bit better than most rich nations in Europe and East Asia.
But along with real productivity, the neoliberal age saw plenty of grift and middle-class wealth extraction. In the book, “Phishing for Phools: The Economics of Manipulation and Deception,” Nobel prize-winning economists George Akerlof and Robert Shiller said that all free-market economies are accompanied by some amount of consumer error, simply because sellers are always exploring every possible method of parting people from their money.
The culprit, as arrived at in the article, was neoliberalism. Surprising to read that in Bloomberg!