And that's if you think this mass spying it's actually working. But so far we haven't seen any evidence that it does. In the vast majority of terrorist "events" they say they've stopped, the mass spying wasn't even essential in learning about them or stopping them. It may have no helped at all.

And for so little benefit, they spend hundreds of billions every year, and get the ability to blackmail or threaten anyone in the world.

So not only is not "not worth it". It's an extremely dangerous monster that should be slain as soon as possible, before it gets to do much more damage than any terrorist could ever do.