What you are describing is called a narrow bank, and it exists in Norway. There were people trying to create narrow banks, but they were rejected by regulators

What you are describing is called a narrow bank, and it exists in Norway. There were people trying to create narrow banks, but they were rejected by regulators, because ,,everybody would take their money out of current banks and put it there’’. Also there is one narrow bank in Norway, if you have at least $50M, maybe big companies should think about voting with their wallets.