Yea there's for sure a market. Beyond what others have said wrt GoPros, many people photograph/stream shows/concerts/etc. Studies have shown you remember events better when you take the intentional act to photograph it, but fiddling with a phone in the moment can be distracting. Why would people want to be focusing on a phone, or be seen with a phone, when they could just watch the event AND get the recording?

I attend concerts a lot, and often post snippets to social media. There's always a tension I see among myself and others of trying to catch those particular lines of a song, while still not missing the show to mess with your phone.

Will I buy these? Meh, maybe. But the appeal is there.