Some folks want to make economics seem complicated. It ain't. Any who, some charts depicting the US economy...through demographics.
First, 15 to 54 year old US population (blue line) and those employed among that population (green line). You may note the end of population growth among them in '07 and not only the end but a significant decline in employment among them since '07. This is the population segment that undertakes most of the credit (creating the new $'s via undertaking debt...vs. elderly who destroy $'s via deleveraging/paying off their loans), buys most the homes, spends the most, earns the most. The lack of growth among them is paramount in understanding what took place in '08 as potential new home buyers ceased to exist and banks gave credit to anyone to keep the party going...'08 (and what has come since) was an entirely predictable demographic caused crisis.