For many years, it was common to have mill towns along the banks of America's rivers. In the early days, a river would power the machinery of the mill through waterwheels. Even after steam power became available, the river was the focus of the town's entire existence. Clean water from upstream provided drinking water, as well as water for the industrial processes. The flow of the river carried human and industrial waste downstream, away from the town, with no cost or effort on the part of the mill owners or townsfolk.
If there was only one town on the river, the system worked well, but as soon as there were two towns on the same river, the downstream town found itself drinking the sewage and industrial waste of the upstream town. Clearly, it was better to be the upstream town.
In a system of uncontrolled capitalism, with everyone looking out for their own good, those who are upstream have no incentive to have concern for those who are downstream. Charity perhaps? Acting as Good Samaritans perhaps? It certainly didn't work out that way for the mill towns.
The analogy of the mill towns fits big banks and many other big businesses today. Those who find themselves on the upstream part of the river are not going to volunteer to clean up after themselves, so those downstream end up drinking their sewage until government steps in to require that everyone stop polluting. After centuries of environmental pollution, our government finally told the upstream companies to stop. It's time for our government to tell the upstream polluters of our financial system to stop.
When told to stop polluting the rivers, the mill owners response was that they couldn't afford to do so. Their profits depended upon dumping their waste into the river, rather than working a little harder to dispose of their waste in a way that didn't pollute the downstream drinking water. The cry was that environmental laws would force them out of business, throwing workers out of jobs. What else could they be expected to say? Certainly not, "Great, let's protect our rivers, we'll just become more efficient, keep hiring workers, and making profits." But after environmental laws were passed and enforced, over the screams of the factory owners, somehow ingenuity quickly found ways to keep the rivers clean and to make big profits.