Fish are a gamble. They swirl their fins, flick their tails and laugh at you underwater; their mouths agape, little laughing bubbles rising to the surface; they know what's coming for them, they know you're on your way with elated spirits and high hopes, and they know they will win, they will crush your heart and ruin your dinner.
All that time spent meticulously tying flies and cooing at the lucky rod, petting luck into every knot and every cast. All the quiet, all the praying, all the hope, flung out into the river only to have the slippery creatures mock your trials.
But at the end of the day, it isn't so much about the fish that pretend to want to bite at the hook, it's about the lust of the river, and hypnotic motion of the rhythmic cast, and the blessing to live in such a place that the fish will still greet you after you've put your hook away.