4：
As long as borrowers can repay their loans before the fixed deposits mature, this game can go on indefinitely. Even if a borrower fails to repay on time, the game can still continue as long as depositors don’t all withdraw their money at once. Or perhaps you decide that lending money is still too risky—what if it doesn’t come back? So, you bundle the loans as "bonds" and sell them to depositors: “These ‘bonds’ are investment products from our bank and offer higher returns than fixed deposits.” In this way, you share a bit of the profit margin while avoiding the risk of non-repayment. Ultimately, as a middleman—or rather, a banker—you must continually innovate in how you manage the flow of funds.

2. The Game of Capital Flow
No matter how you innovate, the ultimate goal is to lend out more money under limited capital. But the game only works if the borrower repays the loan, ideally with interest, on time.