Keynesian economics might make sense in theory. The problem is that in execution folks only pay attention to half of it.
The first half of Keynesian economic theory says that when the economy is sluggish you have major increases in government spending, investment, etc. to help give it a kick start. We love to do that part. The second part says that when the economy takes off again, you cut way back and make up the ground you lost by doing all that over-spending, thus avoiding runaway debt. We never do that part.