I slept on GoPro for a long time because, but then wanted to document some outdoor activities. I went with two Hero 5 units and as a photographer, I was shocked by how overhyped these devices seemed to be.
The first surprise was just shoddy electrical engineering: unlike any camera from a big-name manufacturer, they drain the batteries in storage, to the point where they're dead after 2-3 weeks. But that aside, image quality is just poor for the price. It's oversharpened and oversaturated to cover up deficiencies, and that may work for some YouTube videos, but it's a $400 device that's miles behind any $500 mirrorless.
So I get it that if really want to go snorkeling or mountain biking with a camera, this might be a good choice, but that's a tiny market, and for everything else, why would you buy it? If you want cell phone quality video, you can use your cell phone. If you want professional quality, you can spend the same amount of money on a mirrorless from Canon, Panasonic, Sony, or whatever.
My strong photographer opinion is that you should buy the oldest action camera that meets any resolution/framerate needs and treat it almost like a disposable. Buy on sales or used units. Use them on shots you genuinely are unwilling to use a mirrorless for - strapped to the front of a bike, magnetically attached to the side of a car, strapped to someone jumping in a lake.
The GoPro has always been explicitly marketed as an action camera - to the point that people for a long time called any action camera "a GoPro". Comparing them to smartphones or mirrorless cameras is completely missing their point: nobody would buy them for regular point-and-shoot activity.
You buy a GoPro to mount onto a dirt bike, or on your helmet during caving, or on a chest harness during a skydive, or on the front of your surfboard: all activities where a smartphone or a mirrorless would die on their first use.
GoPro isn't failing because the concept is wrong - the market is massive. GoPro is failing because its competitors started releasing clones which are both better and cheaper. They are the expensive premium brand in a market where buyers expect their product will need to be replaced when it inevitably can't handle the abuse anymore.
the action part of “action camera” is the reason why you buy an action camera. if a normal camera is fine then yeah, you don’t need it.