Imperial Japan made the very same mistake in the lead-up to American entry into WWII. They knew of the industrial capability of the U.S. but figured that with hard enough blows in a quick enough time that they could negotiate a settlement in their favor.
What happened instead was that Japan ensured that American public opinion would support their defeat and ensured it would be essentially unconditional, no matter how long it took and however much it cost.
And if I may turn an argument around for a minute, maybe the lack of Gestapos in the U.S. is a culture of widespread and well-founded skepticism of government power. If we let down our guard then plausibly there will be more Gestapos (as there have been in other, less skeptical countries).
Also, authoritarian governments are far, far more damaging than any individual attack could be. When a government goes wrong it can destroy the lives of its entire population for a generation or more and literally kill millions of people. You can't compare 1:1 the count of individual attacks on a country and the number of times that something like Nazi Germany or Stalinist Russia has happened. They're on completely different scales.
I have never claimed people should let down their guard. I've claimed that people should actually think and reason about an issue and then make a decision, instead of setting up easy (and flawed) rules for hard problems.
I'd be worried if people weren't initially revulsed by stories about government reaching the traditional line at which we declare civil liberties most important. But just as we've moved the line closer to civil liberties and farther away from state power, I don't see how it's automatically totalitarian to even think about moving the line closer to state power if there are actual benefits to be gained and without corresponding higher risk.
Unfortunately it's hard to even debate that here; even where you can get people to agree that it might be possible to consider a risk/reward analysis, they usually take incredible liberties in the logic process.
E.g. the "50 plots foiled; still no details story". It's like, really... you don't think there even 1 possible plot that could only have been detected by grabbing the unencrypted message data from G+/Gmail or Facebook? If someone can't even bother to think critically about aspects contrary to their chosen end state then how can I trust them to debate using critical thought?
I didn't trust Glenn Beck when he tried to use OLIGARHY as a debate tactic; I'm not going to trust people on other issues when they use poor logic either.
Not so fast now. That isn't the only question. Suppose for sake of argument that getting unencrypted data from Google or Facebook was actually a successful method to foil some nonzero number of those plots. The question remains whether that was the only or least intrusive way to stop them. And unless we have the details, we can't make that determination.