Tor users are selected and monitored by the NSA as extremists
I'm not sure why people seem surprised by this.Any sufficiently (i.e. correctly) encrypted content/traffic should be indiscernible from any other of the same scale. While there are ways to infer what sort of traffic is being carried from certain packed inspection and statistical techniques (a bulk HTTP transfer will look different to a peer-to-peer one and both will look very different to an interactive SSH session, and so on) you can't do that for the content.There are five groups using Tor and similar by my understanding (in no particular order): criminals (including terrorists, people  trafficers, illegal drug industry people, and so forth), the oppressed and freedom fighters (depending on your point of view a lot of people in this category might belong in the first one instead and vice-versa), the paranoid who think the whole world is out to get them, those wanting to protect all their content+comms whether secret or not out of principal, and those who are simply experimenting with it (out of "random" interest, academic interest, or because they work in a relevant/related field).The proportion of nefarious types (relative to the total user-base) routinely using Tor is going to be significantly higher then the proportion of such who are not, so the authorities are naturally going to look to Tor for that reason. They are not saying that they think everyone using Tor is a terrorist, they are saying some are but we can't tell who so we are going to check everyone.The only way this will change is if everything is thusly protected, so there will be no difference between the diversity of Tor users and the diversity of the overall population.