The most challenging thing I find about the hobby, is the lack of science and understanding, in many attitudes, and the absence of the want, to progress. There's a few people you meet here and there that truly understand how complex the ocean is, and the creatures we keep, and the requirements they need. But the majority of people, who buy creatures, kill creatures, and then don't give a second thought to "random deaths" are probably only in the hobby because they watched some animated movie about the ocean, and wanted a clownfish.
And then second to that is the reduction of populations in the ocean. Or perhaps money-makers that import countless creatures, and the large amounts of deaths attributed to that.
But then if you were to take a poll, the majority of people would probably swear the hobby saves the ocean. :/
It's pretty sobering at times to be part of that, but until some regulations or rules are solidified to perhaps license people, it's a free for all. Funny part is, there's a LFS near me, who has 12"x12" boxes they keep new stock in, but they cram an insane amount of creatures in it. You can see the more sensitive animals withering away as they don't have enough food in there for their requirements, yet when someone buys something more delicate, the guys there will remark 'just so you know they need daily feedings of pods, or such'. But they don't even do that in the store, and I can only imagine the number of deaths...
Now take those numbers and compound them, and you'll probably be halfway to the amount of corals killed by the "hobby"...