Because they believe that "punching down" (going after "less priviledged" people) is thier SJW-religion equivalent of a mortal sin, while "punching up" is the SJW-religion equivalent of jihad... ...so the most righteous SJW possible would be a morbidly-obese insane person (of color, preferably), as someone so low that they could reeee at everyone they come in contact with, and always be "punching up".