You do realize the tone of your question comes off as intentionally aggressive and inflammatory, right? It’s akin to saying “so why do you beat your wife/children/significant other?” to people you don’t know.

I’m black (well, a mutt) and I hate the systematic abuses done to any minority or anyone at all really, but I don’t have any black lives matter flags, decals, etc despite my agreement with the movement. It’s kinda disingenuous to ascribe something you’ve seen a few do to a whole group or movement.