Regarding exotic pets: Unless an animal has specifically been bred for domestication, its instincts simply can't be accommodated for when kept as a pet. Dogs, cats, some species of rodents, snakes, birds and so on -- they've all been adapted to life with humans through generations of breeding, which has altered their instincts & needs -- and even then, an owner must have a good understandable of the species in order to keep them happy and healthy. Because tigers, ocelots, etc. still maintain all of their wild instincts, regardless of whether they've ever actually lived in the wild, even the carefullest upbringing by a well-educated owner still can't alter what nature has given them. Exotic "pet" enthusiasts can abuse the word "domesticated" all they want, but at the end of the day, what they really have is a heavily stunted wild animal.
Which brings us to another issue: Once raised in captivity, these animals are unable to survive alone in the wild because they haven't learned the necessary skills & behaviors to hunt and/or protect themselves, yet still have needs that are extremely difficult to meet in captive environments. The result is that we have sanctuaries full of rejected exotic "pets" with major behavioral issues, health problems, and so on that can never truly be "cured" -- only managed by experienced animal handlers. They might live a little longer than they would in the wild (depending on how badly the owner screwed them up), but the reduced quality of life really isn't worth the trade-off, particularly when animals don't have any concept of lifespan, mortality and the future like humans do. Living a long life doesn't really mean dick to a creature that only lives in the present.
Worst of all, it also poses a serious risk to humans. Combine the potential aggressiveness stemming from the psychological and psychological problems captive exotic animals are prone to with a lack of natural fear of humans (most wild animals, even dangerous predators, tend towards "flight" responses around humans, since we're unfamiliar and represent an unknown level of risk), and you can easily end up with someone being seriously harmed or killed by your "pet".
ETA: Basically, if the only way to allow your "pet" to thrive is replicating a habitat that is completely unlike the environment humans live in, you're doing a disservice to both yourself and the animal by trying to keep it in captivity.
