Most people don't realize that the NSA is about ten times larger than the CIA. This allows them to aggregate data on a scale that is unprecedented. Being such a

Most people don't realize that the NSA is about ten times larger than the CIA. This allows them to aggregate data on a scale that is unprecedented. Being such a large organization, they still don't have the manpower to process so much data. Thus, the solution is to acquire and store this data for future use. I would imagine that even they don't know exactly what they have.