The NSA has to collect the metadata from all of our phone calls because terrorists, right? And the spy agency absolutely must intercept Skypes you conduct with folks out-of-state, or else terrorism. It must sift through your iCloud data and Facebook status updates too, because Al Qaeda.
Terrorists are everywhere, they are legion, they are dangerous, and, unfortunately, they don't really do any of the stuff described above.
Even though the still-growing surveillance state that sprung up in the wake of 9/11 was enacted almost entirely to "fight terrorism," reports show that the modes of communication that agencies like the NSA are targeting are scarcely used by terrorists at all.
A recent Bloomberg piece points to a 2012 report on terrorism which found that most serious terrorists steer clear of the most obvious platforms—major cell networks, Google, Skype, Facebook, etc.
Or, as Bloomberg more bluntly puts it, the "infrastructure set up by the National Security Agency ... may only be good for gathering information on the stupidest, lowest-ranking of terrorists. The Prism surveillance program focuses on access to the servers of America’s largest Internet companies, which support such popular services as Skype, Gmail and iCloud. These are not the services that truly dangerous elements typically use."
And why would they? Post-911 warrantless wiretapping practices are well known, NSA-style data collection was well-rumored, and we all knew the Department of Homeland Security was already scanning emails for red-flag keywords. Of course terrorists would take precautions. Bloomberg elaborates:
In a January 2012 report titled “Jihadism on the Web: A Breeding Ground for Jihad in the Modern Age,” the Dutch General Intelligence and Security Service drew a convincing picture of an Islamist Web underground centered around “core forums.” These websites are part of the Deep Web, or Undernet, the multitude of online resources not indexed by commonly used search engines.
In 2010, Google estimated that it had indexed just 0.004% of the internet—meaning the vast majority of the web is open for surreptitious message-sending business. Terrorists simply aren't dumb enough to discuss their secret plans over Skype or to email each other confidential information on Gmail.
So, essentially, the NSA is deeply compromising our privacy so that it can do an extremely shitty job of looking for terrorists. Nice.