Why play piano? There are plenty of recordings of people who play better than I ever will.
Why play chess? I will never be able to beat my computer anyway.
Why paint portraits? I will never be as good as Rembrandt, and my camera is infinitely better anyway.
I think the point of the activity is not "I will take the best picture of this plane/the moon that anyone has ever taken". Rather, it's "I will take the best picture that I ever took".