I can understand the confusion. This minigame is sort of a mix between Link's Awakening and Breath of Fire 3's fishing systems. Nothing of those are much in the way of simulators. I am looking at doing a full game of this eventually, and I have more stuff planned for it, but it feels like it's mostly fine for a 5 minute minigame in the middle of a puzzle platformer to spice things up.
As for your reward, you actually don't get any money at all for completing it. You get a summon that increases your speed by 25% when you summon her.