why dont black people like milk?

Because they developed a lactose intolerance from adopting a milkless diet.

Why does OP use the title of his thread as a starter for discussion?

Humans, like most mammals are naturally lactose intolerant. Despite this, several cultures (Europeans/Middle Easterners, African Masai, Steppe Asians) started drinking milk and using other dairy products, and eventually they developed lactose tolerance independent from each other. For black people, the Masai were the ones who mostly herded cattle, the others had no or little access to cattle so they couldn't even begin to develop lactose tolerance.