There are so many people who love going to zoos and circuses. Here's the thing, though. In circuses and zoos, the animals are often there against their will - they have been taken out of a natural environment and brought there for humans entertainment, or have been bred in a captivity that is abusive and enslaving. The animals in these places are treated as commodities. They are kept in cages or environments that are not large enough for them to be able to roam around, and are fed on a schedule that suits their trainer or handlers. This also extends to places like SeaWorld that have whales in captivity in small swimming pool that are much smaller than, you know, the ocean.
There are other options though. I would much rather have animals be in a sanctuary than a zoo or circus. Generally, in a sanctuary the animals will have more space to roam and play, will not be abused or forced into performing for the public, and will generally be treated better than in a zoo or circus.
Don't just take my word for it, though. Read the following articles and do some searching around on your own as well.