[One] reason for allowing the Bush tax cut to expire for people at the top is the most basic of all. Although Wall Street’s excesses were the proximate cause of the Great Recession, its fundamental cause lay in the nation’s widening inequality. For many years, most of the gains of economic growth in America have been going to the top – leaving the nation’s vast middle class with a shrinking portion of total income. (In the 1970s, the top 1 percent received 8 to 9 percent of total income, but thereafter income concentrated so rapidly that by 2007 the top received 23.5 percent of the total.) The only way most Americans could continue to buy most of what they produced was by borrowing. But now that the debt bubble has burst – as it inevitably would – the underlying problem has reemerged.