Your bank can profile you in order to detect someone who isn't you trying to commit fraud by pretending to be you or the ATF can kick down your door and shoot your dog because you made the mistake of buying fertilizer in bulk and renting a truck to go pick it up.

I used to work on tech that could be very useful for someone trying to drop bombs. Our implementation was part of a package that was used defensively, mostly to give the guys on the ground a heads up if someone was speeding toward their checkpoint (go watch some ISIS VBIED videos if you think a few seconds heads up isn't a huge help).

I can shoot someone who breaks into my home (or better yet, nobody breaks into my home when it's common knowledge that most people have the ability to shoot back) or I can shoot someone for illegally dumping a mattress in my alley.

How you use technology really does matter a lot more than the tech itself.