If real GDP continued at its post-war average annual change of three percent, instead of the economy suffering the Great Recession, the U.S. would have realized an additional $15.2 trillion in output vis-a-vis actuals. We can call this the output gap, and it represents what the economy could have produced had growth rates continued.
That accumulated loss translates into job loss, income loss, and, to some extent, bad politics, as evinced by the current crop of GOP presidential candidates.
Real people suffered. And they continue to suffer.