Humans are also the only living beings to go to space. Humans do a lot of things other animals don't do. Why drink milk? Because it was beneficial at one time

Humans are also the only living beings to go to space. Humans do a lot of things other animals don't do. Why drink milk? Because it was beneficial at one time to do so. Milk is a very nutrient dense food, if you were a member of a nomadic culture you'd want food sources you can bring with you, and nutrient dense ones. Many people in the modern world are descended from nomadic groups who consumed milk, so it is a cultural trend that sticks around. I believe it is still beneficial to use dairy products but I don't do it very much because I don't like to keep foods that require refrigeration if I can help it.