It's never made sense to me that some people refuse to drink water even if they know it keeps you functioning properly. The same people will complain of constipation or dry skin but don't want to do the thing that fixes their issues.
Some people don't like the taste? It's like asking why people don't like to exercise even though it's good for them, or they complain about stiffness or what have you. I'm not a huge fan of the taste of water myself, but I drink it because it's good for me and free (once I purchases a filter anyway).