Firstly, how can we be certain?
Suppose, for a moment, I had the data that the NSA has. To whom could I sell that data? If I could prove to questioners that I had such data, to what ends might they go to get it from me(Ans. there are entities that would take it by force and then kill me and my family to remove the traces)?
NSA is sitting on a goldmine. Many, if not most, large corporations, businessmen, academics, organized crime members, politicians, or bureaucrats would sell their home (and possibly their family into slavery) to obtain that information. How can the NSA possibly ensure that it is safe ? How can they ensure that their employees do not pass some of that data to the above? What if a significant chunk of that data is copied and enters the black market? How could it possibly be recaptured?
Snowden has, by example, shown that all the above can and indeed did occur.
As we speak there are undoubtedly hundreds, if not thousands, of individuals who are attempting to gain access to the NSA's treasure vaults. Some groups are smarter and better organized than the NSA. It's merely a matter of time before huge leaks occur. They may or may not be leaked publicly.
Neglect can be criminal too.
And the NSA might not have sent anyone to the gulag but the Obama administration has gone after whistle-blowers at an unprecedented level. Hard to imagine the NSA wasn't helping them out some.
I guess my only option now is to rebel.
But sure for those living in the US they can do that. And they did that with Obama. However that just increased the surveillance.