Why all you have to do is look around. Actually it would be equally productive to search for the fountain of youth, or some such myth. The world is simply not put together that way. Robins eat worms. Thats not fair to the worms.
Spiders eat flies.
Thats not fair to the flies. Cougars kill coyotes. Coyotes kill badgers. Badgers kill mice. Mice kill bugs.