It's just marketing...how many people do you know that keep a single Benjamin laying around much less 10+? The fact is that most of what everyone uses as money is "inside money" that banks conjure up and charge interest on in perpetuity.

The world quickly devolves when the ROC on this benchmark goes flat and the social world heads for chaos when it goes negative.

http://research.stlouisfed.org/fred2/series/TCMDO