Having done some research on the subject, I will contribute...
There are several reasons why the rich are rich in this country, but first some historical perspective.
Following the end of World War II, much of Europe laid in ruins, with little manufacturing capacity left that could be devoted to producing the needed materials to rebuild, let alone progress their society. With the Asian economies at that time not yet having industrialized to the point where they could support the demand coming out of America and Europe (as they can today), the US entered into what most economists and historians call a 'golden age of manufacturing' which lasted into the mid 70's.
At that point, not only had Europe fully rebuilt from World War II, but the Asian economies were industrializing at a fast pace. The statistics showing that are straggering - in 1973, only 7% of the US economy was exposed to international trade and globalization. By 1993, that figure had increased tenfold, and continues to do so. With the rebirth of European manufacturing and the birth of newly industrialized economies in Asia, it is no surprise that the American trade deficit exploded, and with savvy businessmen who knew how to take advantage of it, it is no surprise that the wealth gap started widening dramatically soon after.
As the image at the end of this post shows, the overall percentage of wealth among the richest families (top 10%) stayed relatively stable from 1945 - 1985, staying between 32 and 35%. Even the top 1% stayed stable, between 9-11% over the same period.
Now, I will not begrudge businessmen their right to make a dollar in this economy, but it's somewhat sordid to me that as manufacturing was moved offshore, the income gap began to rise in a hurry, nearly doubling the % of income for the top 1% over a period of 20 years, following nearly a half century where it had remained relatively stable. Moreover, it is an inherently negative thing for the US economy to lose over half of GDP related to manufacturing (26%:1965 to 12%:2009).
Moreso, the strength and length of US recessions over the last 40 years have helped aid the growth of the wealth gap. Between 2000 and 2006 alone the US jost nearly 3 million manufacturing jobs to other low wage countries,which supports the bottom line of businesses and lines executives pockets, but doesn't help the Average American who is trying to get by in this new economic order. And since recessions tend to hit manufacturing jobs the hardest (and those jobs don't return when recovery begins), we are losing a vital part of the American economy, one that has traditionally been a strong source of growth. And since manufacturing jobs also tend to pay more in America than many other kinds of work, we suddenly have less options available for people to make a living wage, further contributing to wealth gap.
It's also interesting to note that the US tax code plays a big role. First off are the de facto (and occasionally de jure) tax incentives that exist for offshoring jobs. Companies that establish subsidiaries in low tax countries pay lower tax if they certify that their profits are invested abroad (i.e, back into the country where that subsidiary was established, not the US). So why stay? Also, by establishing manufacturing operations in low tax countries and manipulating transfer pricing, companies avoid paying US taxes altogether. The tax incentive along with the power of "absolute advantage" creates an irrestible force. The losers, ultimately, are US workers which further balloons the gap between rich and poor.
Also on the table with tax policy is the role of trickle-down economics, the bullshit idea pushed by Reagan and Bush and pretty much every Republican in 2012. The basic (unstated) tenet is simple - shift the tax burden from the rich to the middle class and keep profits high by keeping wages low. Specifically, the bottom 85.4% of households saw 0.1% of the Bush tax cuts from 2001-2006, and during the same time average wages were falling as US companies struggled to remain competitive in a globalized economy.
Finally, there is a huge disconnect in our society between performance and rewards. The argument was given that in order to attract the best people, many jobs (especially executive-level positions) must have astronomical incomes attached to them. But what has the reality been? We all remember the financial collapse in 2007 and the bailouts of big investment banks, but it is not a recent trend. The government bailed out LTCI in 1998, and Drexel Burnham Lambert outright collapsed in 1990. But during all of this, executives have been increasing their own pay, even while company after company either fails or has to be rescued to prevent an economic catastrophe. So while executive pay has increased from 42x the average wage in 1980 to 419x the average wage in 1998 (and even higher since, with many Wall Street banks giving bonuses to their CEO's totalling more than 20 billion dollars during and after the 2007 collapse), their ability to successfully run their businesses has apparently diminished.
On the other end of the spectrum, you have people working 2 and 3 jobs just to make ends meet who are making just a small fraction of what CEO's are making while they run banks and companies into the ground.
The biggest thing we need to do now is find solutions to these problems. Obama has done well in at least recognizing some of these issues, the problem now is just finding ways to address them within the current system of campaign financing (or, short of that, making public funding of elections a priority, something I have supported for a long time).
