The deficit was caused by the financial crisis and the resulting recession, which will cost the U.S. $500 billion a year in tax revenues going forward. Absent the recession, the "trillion dollar deficits" we're worried about now would be half trillion dollar deficits and we'd be talking about how to grow our way out of them.
Absent the recession and absent two wars (one justified but mismanaged so as to still be ongoing even though it should have been a short military operation, one that didn't have to happen at all) those half trillion dollar deficits would be even smaller.