Credit-fuelled bubbles happen when people borrow money to buy things like houses or stocks, causing prices to go up. Lenders give more money as prices rise, making the bubble bigger. Some investors know more than others and take advantage of this by buying overpriced assets to sell later at a profit. Eventually, the bubble bursts, causing unlucky investors to lose money and default on their loans. The study suggests that stricter rules on lending and borrowing can help prevent or reduce these bubbles.