I'm not sure my post yesterday on how the D.C. metro area came to be so rich persuaded anyone, but Dylan Matthews has gone and presented a more rigorous version of the argument with charts and graphs that will finally make it real: The income surge in D.C. is about a surge in spending on influence-peddling that's not matched by a comparable change in the volume or composition of federal spending or regulation.
Maybe a different way of thinking about it from what I wrote yesterday is to go back to a 2003 article by Stephen Ansolabehere, John M. de Figueiredo, and James M. Snyder called "Why Is There So Little Money in U.S. Politics?"
Their somewhat Slatepitches view was that as much as people deplore the high volume of political spending (or at least did in the early aughts, when the bipartisan McCain-Feingold push against "soft money" was in its heyday) that actually the influence-peddling sector seemed to be undercapitalized relative to the stakes. The federal government, they argued, was a really big deal and people weren't spending a commensurate amount of money on trying to shape outcomes. But they were writing a time when the amount of money in politics was already rapidly rising—rising in a way that was alarming people and setting the stage for their contrarian take—and in the intervening decade it's just kept on rising.
A lot of commentators want to see this surge in influence-peddling as reflecting a change in public policy—"big government" has somehow made influence-peddling more worthwhile—but the evidence of past research is that it's simply would-be influencers catching up to a longstanding reality.