Also any other way to earn huge amounts of money?
Define "huge amounts of money."
Most money grinds are either done once a week or take several days of repetition to be generate large amounts. Most also require at least progressing one or more girls' stories a ways to access.
- Maghda has a cave flower garden in her cave, harvest the cave flower nectar weekly after you get rid of Dolf.
- The Family Farm lets you make wine & cheese which can be sold; progress Julia & Annabelle's stories to access them.
- Grind the spider caves daily for venom glands & cave flower nectar; sell them weekly if you don't have a use for them yourself. Progress Erevi to get the quest which opens up the inner spider caves (more spiders = more drops).
- Rent the field, grow pumpkins, harvest, replant; buy honey from Makith; get sacred water from the well; make Energy potions from these; sell the potions to Jenny. Net profit at least 1060 coins/week, more if you include pumpkins/honey you collect elsewhere and/or don't have to have to get Liandra drunk to get the sacred water.
And so on.
If you don't do the goblins storyline you can grind goblin ears in the Goblin Forest, which can generate ~2k coins/pass (can be done twice a day). But this is time consuming even at high levels, expect to spend an hour or more real time per pass through the forest.
If Liandra has been moved into her new home and your goblin tribe is large enough you can generate 1,980 coins/day with no risk. Station goblins guards at the well, fill up on sacred water, sell the water to Jenny for 495 coins; can be done four times/day if you start at the well on Hour 16.
There has to be others I haven't thought of.