Friends or family can't read your mind, but they can steal your physical key.
People putting pins on their phones or password on their laptop are not afraid of being pirated. This is a vague, abstract threat to them. Becoming part of a botnet is really not important to them, and they getting their credit card stolen from the web is really not credible enough for non tech saavy user.
What they are afraid of is other people looking at their stuff. Internet history. Pictures. Their clear text personal document.
Beside, a key is annoying. Where do you think they will store it when they travel ? In the same bag than the laptop. So you steal the bag, you steal the password.