Just around the bend

Why is it that we fly fishermen always think that the fishing will be better somewhere else than where we find ourselves. We say "If I could just get the fly a few feet further out", "If I could only prolong the drift a bit more""I bet the may flies will be hatching just a little bit upstream" and "I´m sure the fish will be rising just around that bend".... well in this case the where rising just around the bend but thats a different story all together...