Yes, you have a point. Do you think it is ok to eat old chickens? Also chicken are born because people raise them. But poor octapuses are just free in a wild.
I used to think a lot about this when I was younger. Somehow with time I accept it better. Still even now I often deeply disturbed by unfairness of it all. Why cannot tigers live happily with deers and all be friends. Why is it like that. I feel so sad when wolfs catch something. Yet when they show their young and that they are hungry and want food I love them too.