> there are dozens of no-brand options on Amazon and Ali that do 4K60fps

I have to very strongly disagree with this sentiment. I have personally tested quite a few no-name "4K 60fps" cameras from Amazon and AliExpress. Many of them upscale from 1080 - which is fine I guess - but then in 60fps will use a crop sensor and upscale from like ~640. Even with the more recognizable SJCam and Akaso brands, unless you're paying ~$200 - you're going to get upscaling, bad color science, bad image distortion. When comparing against a GoPro 5 (first 4k 60 entry) or 8 (first with USB C) the difference is astounding.

Though perhaps this is the difference between good and great that you refer to - but for me, it's certainly worth getting a used GoPro vs any of these modern cheap alternatives.

Unfortunately current new GoPros don't improve on their existing line enough to justify paying current prices. I wish I could get a new 2018 quality GoPro knockoff for <$200

For professional action shots people want 180 degree immersive VR video nowadays.