There was a time when the United States really was the world's richest country by GDP, by median income, and by any other recognizable metric but that total dominance ended by 1973 in which countries such as Sweden and Switzerland surpassed us for the first time in their per capita GDP. The United States is the third most populous nation in the world but its population trails far behind India and China in which both of those countries have only one billion residents each as contrasted to our three hundred and thirteen millions. Population is a key component to a countries' overall GDP in which the United States GDP is double that of their next closest country which is China. However, a Forbes article of 10/7/13 predicts that China's GDP will catch up to the United States by 2020. This won't be the first time that China was the world's largest economy as they had the biggest GDP till around the turn of the 20th century when the baton was handed over to the United States which has not relinquished it since.
In the 21st century we can see that the United States has continued to slip down the charts, for instance, in 2000, the United States was ranked by Credit Suisse as the #1 in average wealth per adult, but by 2010, the USA had slipped to #7 with an average of $236K which was behind countries such as Switzerland, Australia, and France. For 2012, Credit Suisse stated that the United States median wealth per adult was at $38.8K which was ranked 27th in the world, surprisingly behind such countries as Germany, Sweden, Japan, and the United Kingdom.
Which leads us to the next problem for the United States which is that out of 50 countries, only Russia had a larger disparity between average wealth and median wealth in which the ratio for Russia was 12.6 times its median wealth, whereas in the United States it stands at 6.7 times, in contrast to Australia and the United Kingdom in which they are at 1.8 times and 2.2 times median wealth respectively. (Remember that the median is defined by having half of the numbers above the median and half of the numbers below the median, therefore the closer an average salary is to the median, the more equitable the number; the higher the disparity the more inequitable, because an average takes all of the numbers together and divides them by the quantity of numbers taken.)
This disparity between average and median wealth is part of the reason why the United States is perceived as wealthier than it really is. America is very wealthy for the special elite, in which the United States is first in billionaires, and first in millionaires, and their conspicuous consumption is felt worldwide. But America also has an impoverished underclass in which a report issued in 2011 by the Organization for Economic and Cooperation Development stated that our poverty rate was more than twice that of countries such as Denmark and Hungry, and our poverty level was higher than countries such as Germany and Italy.
Marcus Aurelius said that "poverty is the mother of crime." We can see that in our prisons which are full, this despite a country that is widely acknowledged and perceived as being the richest nation that the world has ever known. America is a country divided by rich and poor, with a middle class being squeezed out of existence by taxes domestically and labor outsourced internationally. America is great and is impoverished, unfair, corrupt, and heading for the shoals.