The article discusses how sudden economic crises in the 1990s led to the 2008 global financial crisis. It explains that these crises happen when countries can't borrow money anymore, causing big economic downturns. The researchers used models to show that these crises happen when debt gets too high compared to how much money or assets a country has. This leads to a cycle where falling prices make the situation worse. The study also shows that people don't think about how their borrowing decisions can affect future financial problems.