Gee, that "trickle down" idea from the 1980's has worked out a treat.
Go ahead and shrug your shoulders, libertarians.
Update: from the blog post at the LSE by Saez and Zucman on their work:
The growing indebtedness of most Americans is the main reason behind the erosion of the wealth share of the bottom 90 percent of families. Many middle class families own homes and have pensions, but too many of these families also have much higher mortgages to repay and much higher consumer credit and student loans to service than before. For a time, rising indebtedness was compensated by the increase in the market value of the assets of middle-class families. The average wealth of bottom 90 percent of families jumped during the stock-market bubble of the late 1990s and the housing bubble of the early 2000s. But it then collapsed during and after the Great Recession of 2007-2009. (See Figure 2.) Since then, there has been no recovery in the wealth of the middle class and the poor. The average wealth of the bottom 90 percent of families is equal to $80,000 in 2012—the same level as in 1986. In contrast, the average wealth for the top 1 percent more than tripled between 1980 and 2012.Update 2: ah, I see it was Saez & Zucman who Cato and the WSJ were attacking mid year about their figures for calculating wealth. This working paper release presumably gives the details of what was in the powerpoint presentation Piketty was referring people to.
How can we explain the growing disparity in American wealth? The answer is that the combination of higher income inequality alongside a growing disparity in the ability to save for most Americans is fuelling the explosion in wealth inequality. For the bottom 90 percent of families, real wage gains (after factoring in inflation) were very limited over the past three decades, but for the top 1 percent real wages grew fast. In addition, the saving rate of middle class and lower class families collapsed over the same period while it remained substantial at the top. Today, the top 1 percent families save about 35 percent of their income, while bottom 90 percent families save about zero.
If income inequality stays high and if the saving rate of the bottom 90 percent of families remains low then wealth disparity will keep increasing. Ten or twenty years from now, all the gains in wealth democratization achieved during the New Deal and the post-war decades could be lost. While the rich would be extremely rich, ordinary families would own next to nothing, with debts almost as high as their assets.
What should be done to avoid this dystopian future? We need policies that reduce the concentration of wealth, prevent the transformation of self-made wealth into inherited fortunes, and encourage savings among the middle class. First, current preferential tax rates on capital income compared to wage income are hard to defend in light of the rise of wealth inequality and the very high savings rate of the wealthy. Second, estate taxation is the most direct tool to prevent self-made fortunes from becoming inherited wealth—the least justifiable form of inequality in the American meritocratic ideal. Progressive estate and income taxation were the key tools that reduced the concentration of wealth after the Great Depression. The same proven tools are needed again today.