There is a vulnerability called BlueBorne that is a vulnerability in Android phones and Apple devices that aren’t upgraded to iOS 10. When it’s left turned on, people can use it to connect to it and sometimes through cars as well. They say when it’s not in use, turn it off. It’s interesting to read this because I usually leave it on and don’t think about it but now that reading this, I would turn it off and on my laptop too.
https://lifehacker.com/stop-leaving-your-smartphones-bluetooth-on-1817176967/amp