Because I personally don’t want to eat 80 grapes. Besides the sugar content of 80 grapes is not healthy.
That's just wrong, sorry. Demonizing fruits is one of the most dangerous "health trends" on the face of the planet. Right up there with antivaxxers.
And, again you can eat leaves which don't have sugar and have lots of other great nutrients and fiber, while having less water volume.
No one is forcing you to drink it.
You just haven't encountered that kind of peer pressure yet.
For context on the reference: https://www.reddit.com/r/Teachers/comments/1but3c2/wait_zoomers_actually_cant_read_analogue_clocks_i/