Kapernick and many other players ARE putting up cash too,
Kaepernick said he was donating a million dollars to "good causes." To my knowledge, he has never said what "good causes" and when he was asked about it shortly after everyone started talking about his protest, he seemed caught off guard by the question. His response sounded more like someone trying to make it go away than someone who had actually planned something.
Maybe he's picked his good causes and started sending money. If so, good for him.