Yes - I did realize what your point was - I was kinda adding onto an interesting fact - most people do not realize that killer whales are actually dolphins.
I have a good friend whose job is essentially researching whales, trying to protect them and their habitats - a whale expert. She talks at length about how unlike many other animals, dolphins actually have a shorter life span when they perform and live in tanks and so forth (rather than living in the wild). It is actually extremely stressful for them to perform - most likely why they "go crazy".
Just think about it - like other wild animals - you put them in an unnatural environment, force them to perform and you expect them to be happy? Try caging your children and having them perform (well I guess will do that with child actors and see how successful they are as adults on average)...