Bruce Schneier

If you're a filmmaker, and every time you finish a film, you just naturally go, 'Oh, I could have done so much better,' that's not much fun, is it, really? You might as well go pick another profession if that really is how you derive satisfaction from it.

Every time you log in to Facebook, every time you click on your News Feed, every time you Like a photo, every time you send anything via Messenger, you add another data point to the galaxy they already have regarding you and your behavior.