NSA mass surveillance was not just a matter of "wiretap some central points on the internet" as a one-and-done operation. It required thousands of people to work on various infrastructure and operations and to maintain it on an indefinite ongoing basis. It actually would have required far more sophistication and coordination to keep quiet in perpetuity than doing 9/11.

However, in point of fact, mass surveillance actually was kept quiet for years after it was spun up. Long after the evidence had leaked from multiple sources and become undeniable, you would still be called a crackpot if you said to someone on the street that all their electronic communications were being collected and stored indefinitely. Then, on a certain day in 2013, a former CIA employee dumped the NSA's files to the Western press, which obligingly flipped the narrative and dedicated weeks of extensive coverage to the government's shiny, new, and by then well entrenched panopticon. A surveillance system is ultimately most useful in its purpose only if the people know they're being watched, and the time had come for it to be unveiled.

As always, a large amount of media coverage in mainstream press outlets was a good indicator of what it was that the state wanted people focused on. The massively lower level of attention drawn to the Vault 7 leaks (which were arguably even more crucial than Snowden's) is stark and instructive, as is the different fate of the whistleblower (obscurity in prison vs international celebrity status) and a good indication of what they don't want you thinking about.

"Use Signal, use Tor."