I am going to say that the majority of the people who get these fish can not house them for their full life- but another point to look at, is a lot of fish that are captive bred don't reach their full "wild caught" potential. I'm not saying that a goonch that gets to be 80" is going to only get to be 20"- not at all- I would just shave off about 6 or so inches from the full expectancy length.
Now, do I have the room to house a goonch? Yes, but will I keep that set up forever? No. And chances are, most of us aren't going to. In a matter of fact, I am tearing it apart once my pond is complete.
We will do what we have to, in order to keep the fish we love. Yes, there are a lot of fish that I like, but I am not going to keep up a huge setup for a fish I only "like". Now, you give me a sturgeon, and I will buy it a seaworld tank! I absolutely LOVE those fish.
I really just think that a lot of people get them spur of the moment because they are cool, and get them BEFORE doing research, and then afterwards, they are like "oh man, what did I get myself into?"
The key thing is to do your research, and accommodate the fish that you can properly!