I also used bitlocker on my laptops and on customers’. Same as Alex, it’s about machines being stolen.
Unfortunately I probably now can’t get into a ten year old Lenovo top-end laptop because I’ve probably forgotten the admin password.
@parkdale - Indeed that’s absolutely true, bitlocker won’t protect you; it’s totally irrelevant. Ransomware will need to be run by an admin to encrypt the whole drive, otherwise it will just encrypt the files the current user has access to, which will typically be a lot so disastrous. It doesn’t matter in the slightest whether or not you have bitlocker turned on as it’s just a normal application modifying files through normal o/s API routines that ordinary users have access to.
Mind you, if you tried to boot ransomware from another removable drive then I’d have to think about that. I suspect bitlocker would protect you, but the ransomware could just burn your file system perhaps, not sure, would have to think about that.
IMPORTANT: If using bitlocker, you should make sure the BIOS settings are such that you can’t boot from any removable drive, and the BIOS UI has a strong password so evildoers can’t get in and modify the settings. But then anyone should always do that! And make sure to record the password on another machine somewhere where you won’t forget it’s location.