Along with adding more mass to the planet. What do they think will happen if they add more water to the planet? The water levels will rise. The world climate cycle keeps water shifting, as well as transforming it between solid, liquid and gas. The amount of water also stays at more or less a constant amount I’d assume. Adding more would burden the world’s climate, and really change it irreversibly.
This isn’t hard to figure out.
I try to drink my share of it, but I end up just putting it back down into the ground at the end of the day.