The terrorists absolutely won. Least that's my perception as a non-American. Your first mistake was legitimising them as "the enemy"
When the IRA were bombing Docklands, Manchester or Birmingham pubs we'd make a poor taste joke the next morning, walk past the wreckage and forget about it the day after that. When the Baader Meinhoff Group were killing public figures, and bombing Brits, Germans and Americans over in Germany they were treated as a bunch of insignificant extremists. Even by the Americans it seemed from news reports. There'd be a poor taste joke or two, and they'd be ignored. Much the same for other terrorist groups hijacking aircraft or killing people through history. "Don't deal with terrorists" was heard from every politician.
Then came 11/9 and the "war on terror." So determined were your politicians to legitimise the terrorists it became a war. Against a legitimate target. Globally. So determined were you to preserve your "freedoms" that you built an apparatus of surveillance to ensure that freedom. Apparatus so far reaching that it is indistinguishable from an apparatus of oppression. Most other countries played along too in support, and built the same apparatus of oppression to preserve freedom. Not only did the USA lose, and the terrorists win, but the UK, France, Iraq, Malaysia etc lost too. So did freedom.
No more bad taste joke the morning after and treating them as a bunch of irrelevant idiots unworthy of but the briefest air time (like I get the impression most Americans still do with a group like the Westborough Baptist Church), but an unwinnable war with a legitimate enemy and a leader, and endless analysis. Everyone except them, globally, lost.