Buy now. Pay (and pay, and pay, and pay) later.

What happens when you convince a generation to spend more than it can afford? We’ve seen this movie before. Literally. The Big Short, based on Michael Lewis’s book about the 2008 mortgage crisis, features Steve Carell and his hedge-fund lieutenants talking to mortgage brokers about home loans. “Do applicants ever get rejected?” The brokers laugh. “If they get rejected, I suck at my job.” Carell asks if their clients have any idea what they are buying. “I focus on immigrants,” one responds. “Once they find out they’re getting a home, they sign where you tell them to sign. Don’t ask questions, don’t understand the rates.” Someone adds: “Fucking idiots.”

Sound familiar? Money-obsessed finance bros covering their eyes as they exploit financial illiteracy? Good times — as long as the lines on the graphs are all pointing up. But when the market turns, contagion spreads. U.S. job losses in 2008 were the worst in half a century. Millennials are still digging out of the economic blast crater. Now their younger siblings are wondering what that ticking sound is in their inboxes. It’s the arrival of past-due notices from Klarna. Listen, because when this debt bomb detonates, the shrapnel could disperse far and wide.