If you think the economics of banks are that simple, you are very wrong, the economics of banks are so complex that even imagining it is sickening.
Complex if you explore every part of it, but for us, one who uses banks it is pretty clear. Banks are designed to make money, not to store. So if you are one of their customers, you are part of their large scheme. Sickening, big YES, Imagine depositing in a bank, you take a loan and they put interest on that loan, basically you are paying interest from your money.
But as far as I understand, the banks park their money mostly in securities and loans to their customers, then some in investments, businesses, etc. And because of this, during an economic crisis, many banks will limit their customers from making loans and withdrawing money, because most of their money is somewhere else and when everyone withdraws money from them it means it will disrupt their operations and could cause them to collapse.
Banks are businesses around the world, tbanks do invest the money from their depositors and make that money grow while making money with their customers from charges of keeping their money. If you read the terms and agreement when a crisis happen, you'll understand that you don't matter to them as long as they are continue earning. Bankruptcy affects their customer not them, it is not their money in the first place, customers are the bank, and behind those are just puppeters.