Sure they do, that’s the problem. For centuries in America, Black Lives have been seen as less than white lives. “Black Lives Matter” is simply a humble request to value the lives of Black people, and not treat them as 3/5ths, or any other value less than fully equal to your life.
If you’re angry about this, you’re actually angry at the country you live in being so horrible to people not like you for literally centuries. Please get real.
Not convinced? Read “Why you should stop saying ‘all lives matter,’ explained in 9 different ways” by German Lopez.