Who says hero 4 is much better than xiaomi yi?

Who says hero 4 is always the best for action camera? Yes I agree that hero 4 is a pioneer for the action camera from my opinion. And let me introduce to you, a $80 action camera that has a better quality from my perspective compare to hero 4 silver and black in 1080p. This all pure recorded with my xiaomi yi. Which one you will pick, $399 hero 4 silver or $80 Xiaomi Yi?