-Facial recognition (increasingly used to unlock devices)
-Recording keystrokes to gain access to passwords, bank accounts etc.
-Companies checking up on employees to make sure they're really working
-Store images and videos of people undressed/doing something compromising, for blackmail or upload to other sites
-A few years back a student sued his/her PA school for secretly spying with school-supplied laptop, which turned out to be a school-wide thing


Here's an article from howtogeek that might help: https://www.howtogeek.com/210921/how-to-disable-your-webcam-and-why-you-should/

Incidentally I just put a piece of tape over my webcam too. Disabling it doesn't seem necessary.

It could be used for blackmail.
I once read that it is not hard for hackers to access your mic or cam. In contrast to celebrities/people like Zuckerberg, they might not be interested specifically in you and me. But this where the shift in thinking has to come. It's not about concentrating on how low the possibility is that there could be someone targetting you or who that might be. It's more important to aquire the mindset that this breach of privacy is possible and that your actions should be done with that in mind. I hate that almost all laptops come with built in webcams. I haven't covered it on all devices because it might make one look a little bit paranoid but I act according to the possibility (even if it's very small) that it could be hacked.

It's just like with personal information in the online world or private info on phones. For the majority of people, there is no reason to target them specifically. Just act with the knowledge that the information you put online in any form is not private.