Because:

1. His claims are really in the weeds. You have to spend a lot of time breaking down everything he says to really understand it. It's more complicated than "government spying, government bad". Scott Adams makes a good point about this. If some issue becomes so complicated that, in order to see the truth, you have to get in the weeds, it's not going to register with the public at large, because they have other things to do and can't spend that much time on it.
2. People don't actually care as much about their privacy as we typically like to believe.
3. The government really wants its spying powers, and so politicians aren't really pressed to change anything. Few politicians get elected on a "tear down government spying" platform or lose an election by not being pro-privacy enough. However, politicians are desperately afraid of losing an election because some terrorist murders thousands of people because the government didn't have enough intel and was blindsided.

Just look at all the "shortcuts" the intel community took to wiretrap the Trump campaign during the 2016 election, believing that anyone who was even remotely pro-Russia and in Trump's orbit must be a secret KGB agent trying to infiltrate the US. The FBI was able to obtain secret FISA warrants for Carter Page, Michael Flynn and others using evidence that was later found to be just rumors and outright political smears by Hillary supporters or Trump political opponents like Christopher Steele.