There's no reason to violently attack someone like that when they are not a direct threat. I think it shows a great deal of immaturity if you believe that attacking random people is righteous in any way. As Lubab said, it's also very hateful to attack an individual just because they're black, and you wouldn't want that done to you. How is hating someone that fiercely just because they're black any different from hating someone fiercely just because they're Jewish? How you are you better than an anti-Semite if you want to physically harm or kill someone just because of who they were born as?