The answer to that question is easy to answer. America is the most unequal rich nation in the world. The only income group that did not experience a decline in income between 2000 and 2013 is the top 10%. The real income of the bottom 90% declined during this period. The decline was greater for the groups near the bottom of the distribution. The low income groups were called "moochers" by Mitt Romney during his presidential campaign because they qualify for government programs that supplement their income. He told a group of wealthy contributors that his political party is their political party and that he would cut their taxes and the government programs which made life a little better for the "moochers". What he did not tell them was that the federal government collects much less tax revenue than other rich countries, and that it redistributes less money to its less advantaged citizens than any of the countries in OECD. The distribution of income, including benefits from social programs, is less equal than the distribution of market income in the US. It is the least equal among OECD nations in the distribution of total income which includes government subsidies.
It did not help Romney's campaign when his statement was leaked to the public. Some of the "moochers" may have decided not to vote for him. He told his wealthy backers what they wanted to hear but his campaign never recovered from the publicity given to his comment which was only intended for his major contributors. His political party cannot win elections unless it convinces a lot of the "moochers" to vote for its candidates. Unfortunately, his political party is well funded by its wealthy supporters. It has been able to convince many of the "moochers" to vote against their economic interest. Like most people, they hate taxes and they have lost trust in government. They also don't want their tax dollars to fund programs that help the "wrong kind of people". They identify more with the rich than they do with the class to which they belong and to which they expect to leave when they get rich.
The mid-term elections in the US will only increase the level of inequality in America. The war against the "moochers" will get even worse with Mitt Romney's political party controlling Congress and many of the state houses in our country. The American Dream was once somewhat connected to reality. Today it is mostly a dream. The nation that inspired the rest of the world with the dream of democracy is losing its ability to inspire, and to lead, as the dream of democracy fades during its move into the "New Gilded Age".