Humans are the only living species on this planet where the adults drink milk.

No doubt. The food nutrition industry has been hijacked by vegans, animal rights activists, and climate alarmists. Pretty much everything that demonizes animal product is a lie, especially when it's spread by vegans. E.g:

1) "Cows are major contributor of GHG" - Wrong. Crop agriculture produces more GHG.
2) "But crops are grown to feed livestock" - Wrong. over 80% of plants fed to livestock are inedible by humans.
3) "Eating meat will give you heart attack!" - Wrong. Humans have been hypercarnivores for the vast majority of our existence.

And dozens more lies that pushes humanity towards eating processed crap. I bet the vast majority of people don't even know their food is mixed with sawdust.

https://www.npr.org/sections/thesalt/2014/0...ating-wood-pulp
https://www.prevention.com/food-nutrition/h...ontain-sawdust/

We don't see adult cows drinking milk though. Also, cats probably don't even know it's milk.