Second, there are structural theories, including those of institutional economics, that point to underconsumption and over-investment (economic bubble), or to malfeasance by bankers and industrialists.
Plus fraud, embezzlement, conspiracies and money-grubbing on a monumental scale, by a host of breathtakingly high-paid bankers, financiers and corporate kingpins.
You already see very loose lendings starting, trying to emerge in the crisis there is something called the government-like-loan where bankers lent money without writing in any strong governance.