I think you're thinking about this a bit naively, concentrating on the utility without considering the detriments.

Look at social media. WE are the ones who surveil ourselves. Yes, the big social media companies process all that data and use it against us, but we are the ones who give the pictures, videos, and words to them. There's really no good way around this either. I put those same things on my blog and they still get scrapped.

So what ends up being the difference? It's not synced to the cloud, but we put it there anyways. Do you really think most people are just going to take the videos and not share them? Do you think most people are just going to run a NAS at home? In an ideal world, yes. But I don't think we're anywhere near that happening. So a good portion of those videos just get put online somewhere and bad actors have access.

Non-volatile recording doesn't really exist. We're on HN and I'd expect most people here to be familiar with how easy it is to download a streamed video. yt-dlp will do that for a lot more than youtube.