Declining Declinism?

I don't entirely agree with Alan W. Dowd on the decline of declinism since he tends to gloss over the significant threat from terrorism and the potential impact of a major attack. He does, however, put matters into perspective:

Just consider what the U.S. economy has lost since 9/11. One estimate posited that by the end of 2003 the U.S. could have lost as much as $500 billion dollars in GDP as a result of 9/11. That’s roughly the size of the entire Iranian economy or half the Canadian economy.

As to Katrina, Congress poured $122 billion into the vast disaster area—and that was just in the 12 months immediately following the storm.

None of this was budgeted or foreseen, yet the U.S. economy dusted itself off and soldiered on.
While the declinists routinely remind us that the U.S. spends more on defense than the next 15 countries combined, they seldom note that the current defense budget accounts for barely four percent of GDP—a smaller percentage than the U.S. spent on defense at any time during the Cold War. In fact, defense outlays consumed as much as 10 percent of GDP in the 1950s, and 6 percent in the 1980s.