The scary part is that you can't protect yourself easily from those around you. For example, let's say you like to maintain your privacy, and you're careful about anything you post online, you're careful not to have an always on microphone, such as the Echo, you're careful not to have a smart television with a video camera connected to the internet in your living room, etc. That's great, and up to you to decide, but what about your friends house?
I mean, when you visit your friend, stop at a girlfriends apartment, or hang out with people at the pub, are you checking if they have any of these devices? Do you search their shelves for an Echo? Do you ask everyone at the restaurant if they have a smartphone with a microphone connected to the internet?
It's impossible to avoid things like this in your life. The second you walk outside, you're surrounded by cameras and microphones that can be streaming anything, to anyone.
Facebook is another example. You might say, I don't want to enter where I live, or where I went to school, I feel that's sensitive information. Well, since you refuse to give up that information, Facebook just encourages your friends to squeal. Hey, does John Doe live in X or Y city? Did you go to university with John Doe? Hey, why don't you upload more photos of John Doe, and tell us the time and location that photo was taken. Actually, no need to tag him, we'll just detect his face, and use the date the photo was created.
It's not going to be long until you can search a person, and see a timeline of their life based on data from third parties. Let's watch John Doe's life for 2018. Oh look, Jan 15, he appears in the background of a tourists photo by the Eiffel tower. Jan 21st, we detected is face on the metro in southern France. Oh, Jan 28th, a car dash cam finds him walking down a street in Italy. Oh, his phone was on and we can see he was in Jane's apartment Feb 1st. Let's pull the audio from the microphone on Jane's television for that day.