The excess dollars in circulation tend to be absorbed by treasury bonds, which is backed by the US taxpayer. If there were doubt about this tax base, then the

The excess dollars in circulation tend to be absorbed by treasury bonds, which is backed by the US taxpayer. If there were doubt about this tax base, then the dollars would stay in circulation and devalue the currency. Of course inflation still happens, but it is controlled to a low level which economists claim is helpful to spurring the economy.