Maybe there's a way to better way to boycott... we could just not spend any money, or, we could get the insider information on the loss leaders, and all things being equal, buy only the items that show up in the red. We get a great deal, feel good about sticking it to them, and we won't have any arguments about virtue signaling, etc.
The boycotting IS working as evidenced by the fact that Dick's is struggling. The struggle would be over and they would be closed if every gun owner would simply not shop there period.