It's a mystery to me how banks make money in this era, where all their loan activity is. It doesn't seem like banks like Wells Fargo loan to businesses much anymore, at least not small to medium sized businesses. And now the end of the personal lines of credit further removes them from the classic role of a bank.
Banks used to issue their own currencies up to about the early 1900s, mostly in the 1800s. This was in the US, Europe, really everywhere. In the US the banks were fundamentally sabotaged by requirements that they buy state government securities, bonds, etc. issued by the state they were in. This distorted the industry and compromised banks' ability to make rational investment decisions, forcing them to buy subpar government instruments, and this contributed to their instability. Banks in Scotland and Hong Kong still issue their own private currencies, but they're based on the core government currency, not truly private or free market.
Without issuing currencies, modern American banks seem strange to me. They're like branches of the Federal Reserve, just with some minor differentiation on how they package their accounts, features, logos and color schemes, etc. They all get money from the Fed via mechanisms I've never fully understood, they have reserve accounts with the Fed that seem like arbitrary Monopoly money, and so forth. What makes one bank more profitable than another is a mystery to me. The mortgage crisis exposed some ways they made money, but that seemed like a fluctuation, not a normal forever thing. It will be interesting to see how banking evolves from here. I'd love to see more innovation and fewer barriers to entry. These big incumbents have coercive monopolies because it's almost impossible for anyone to start a bank in the US. I'd also like to see private currencies, with a lot more transparency about supply – there's no compelling reason to have permanent, chronic inflation in prices, and lots of reasons to prefer a stable or slightly deflationary currency.
Bank just package their stuff and sell it as investment product to someone else. They like to make a cut of something they borrow from someone and then lend to others, then send it off when things blow up. This is the main reason I do not like to buy investment products although I sort of have to with 401k.
Oh, the Fed print far more than you deposit, and the international market buy far more investment products than your petty IRA and 401k with contribution limit.