At least in my circles of people who are relatively well to do, yes, quite a few bought Chinese knockoffs on online retailers like Amazon. Hell, when you search GoPro on Amazon Canada a Chinese knockoff is the first result and has over a thousand more reviews than the actual GoPro!
I imagine now or sometime last year would have been about when I naturally would have upgraded, and I suspect if I had seen a ton of reviews favoring cheaper models from competitors, I probably would have jumped ship.
Maybe that is just a hindsight is 20/20 situation since I work in a tangentially related industry that is also greatly affected by Chinese companies pumping out cheaper products. But they have had plenty of time to realize this and change course.
the yi 4k+ also does that but no it isn't waterproof by itself, however you can see the hero 6 got a $100 price cut because of the stiff competition
https://www.marketwatch.com/story/gopro-shares-pare-huge-los...