Yep. It's no different than regular crime. We could prevent all crime if the state handcuffed every single citizen. Done! Yay! Whoops, except we destroyed what we meant to protect: life and liberty.
That's what surveillance is doing now. It destroys freedom of speech, freedom to gather peacefully, freedom to petition the government for a redress of grievances (how can you investigate government wrongdoing if they're tapping your phone?), all to (possibly) mitigate the already-small risk of being blown up by loonies.