Some people are addicted to sugar to the point where every beverage must be sweet flavoured.

I have water, but othertimes I am sugar addicted so I want a different beverage.

Also I have had tap water in various places across Canada. Most are decent, some are especially delicious, some have awful after tastes and even smell weird (sulfur or chlorine). If that stuff runs to your home I can understand why people prefer bottled water, tea or soda instead of tap water.