I believe that most Zoos around the world were made to serve the purpose of entertaining human beings and not for protecting wild animals and their habitat.
In fact, Zoos are more like jails for animals where they are fed, bred and tamed to raise money for humans.
Quite often we can see on the news about zookeepers mistreating animals. Instead of protecting these animals with the respect of treating them as wild beasts, most zookeepers domesticate them so that they can be handled easily. These animals are controlled in small cages or in limited spaces. The poor beasts will think that there is nothing outside of their cages and shelter. They are exposed to human beings like a window show. Let us reverse the situation and see through the eyes of these animals like in the “Movie planet of the Apes” where we are the ones in the Zoo cages and they are the spectators. How terrible would this be? Just imagine for 3 minutes, We human beings of sophisticated intelligence would be so stressed that we would probably die early.

The next reason why Zoos aren't protecting wild animals is that Zoos make animals lose their natural instinct.
When animals are kept in the zoo, they become too dependent on human beings and their surroundings. They will also multiply in this kind of environment. On and on, the new ones who have never experienced the wild will naturally think that the Zoo is their homes. Eventually, these animals in the Zoos will never be able to mix with those animals of their kind in the habitat that they originally belong to.

We have seen in many cases where human beings try to control, things do not end up well. Zoos are certainly one of them.