How many whales are there on earth? How many lions? 50,000 at most. You could put a bullet in the head of every lion on earth tomorrow and it would be a drop in the ocean compared to the hundreds of millions of farm animals that would be killed _on that same day_. And the lions at least wouldn’t have spent their lives packed 10 to a square foot in a barn dying to sickness.
There are some incredible, highly regarded documentaries (planet earth, blue planet) that do far more for educating people about animals than viewing that animal in a cage ever can. If zoos actually created any sort of compassion in visitors for animals then we wouldn’t be having this argument — all they create is fascination in a select few species we’ve deemed to be interesting enough, and what use is that to the animals being tortured on a scale millions of times greater.
Exotic animals are just a tool used to support an entire species cognitive dissonance.