If nobody spent money the economy would implode in a matter of minutes.
Yes, that is true of a a debt based economy, quite scary really.
A debt based economy can only survive with ever increasing expenditure, and so we see resources wasted and asses too fat.
If you want to know the math explained simply then check out this video:
http://www.youtube.com/watch?v=jqvKjsIxT_8