You do know its possible to catch 2-5 star fish without any upgrades right... The main game mechanic involves the red and green line when you hook a fish. As the bar fills up, it turns red, indicating that the tension of the line is high and it might snap. As soon as you let go, it turns green, and you basiclly gotta edge it until you catch the fish. The upgrades simply make that process easier. I caught a 5 star fish without any upgrades on my second run, after i noticed this mechanic. It wasn't easy but it is possible. That being said, the learning curve is steep as I feel the weather patterns simply make it too difficult to make enough of a profit during the begininning.