The business of banks is basically a loan sharking business. They use the deposits on hand to lend money to people or businesses that need money, and then charge them interest that is much higher than the interest they pay to depositors. This is their main way to make money - earning the difference.
Look around, no matter whether the economy is good or bad, people always need money. Businesses need to expand, buy equipment, or replenish cash flow, and individuals may also need money to buy a house, a car, or pay tuition. The bank stands here, extends its hand and says, "Do you need money? I can lend it to you, but you have to pay a high interest rate." In this case, the bank is like a never-ending market, and there will always be someone who needs their "help."
And it's not just a simple matter of lending money. Banks also use this method to build and deepen relationships with customers, and then sell them more financial products, such as insurance, investment accounts, etc. In this way, banks not only make profits on loans, but also earn more service fees and handling fees from customers.
In the whole process, banks seem to always win. They use sophisticated risk assessments to choose who deserves loans and use various complex terms to ensure that they are always on the safe side. If the borrower cannot repay the loan, the bank can also reclaim the collateral for the loan, such as a property or a car. In this way, the bank can get money in many cases while minimizing the risk.
In short, the way banks make money through lending is not only to earn the difference between them and depositors, but also to put themselves in a position where they almost always make money. This is why some people feel that banks seem to only know how to lend, because this is their magic weapon for winning money.