The MC Rockefeller is someone with gray morality when it comes to money. His father is a tax collector and his grandfather is a famous doctor. He is the eldest of five siblings where his oldest younger brother goes to the military and married the daughter of the debt-ridden lord of the land they're living in by exchanging the rights to manage and the MC taking responsibility of the lord's debt, the second oldest younger brother became the MC's right hand man, the third oldest younger brother became a priest due to his desire to repent in the place of his siblings instead, and the youngest has shown interest in getting involved with the imperial court. In the beginning, the MC and his siblings went to a nearby stream to get placer golds out of desperation, and succeeded in collecting a large amount of it which he secretly exchanged with a goldsmith named Carter by projecting himself as a middle-man for an imaginary smuggler. The dealings continued for a while before the MC decided to become the goldsmith's assistant which raised the profits of the bank that the goldsmith managed through several schemes the MC orchestrated. The schemes are burying the lord to debt with the land as collateral, introduction of paper currency in order to expand the loaning business and get the lord into debt, short-term monopolization of beer to sell to dwarves, and having the local church deposit their assets to the bank with positive 3 percent interest. Several years have passed and the MC managed to usurp the management rights from the lord by marrying his brother to the only child of the lord. A sudden earthquake revealed a massive gold vein located in the MC's territory so he went to one of the largest guilds whom his bank is a member of, to get more power to deal with it but the guild leader is an as*hole so he replaced him with the support of the church and several other guild members that are disgruntled with the now-former guild leader. After becoming the guild leader, the MC introduced modern banking techniques and wages financial wars with other rivaling banking guilds.

I haven't mentioned a lot of details so read the novel if you want to find out.