"what exactly have they accomplished? zero"

So far, you might be right, TLT.
Like Emmett Till, Rosa Parks, the Freedom Riders and many others, Colin Kaepernick has paid a price for pushing against the prevailing white boundaries. If Trump has his way, others who dare to dissent will be fired and out-cast.
Time will tell... it took almost a decade between Rosa's refusal and MLK's Dream.

Nobody said that correcting injustice is easy.
Ever.