It has long been argued in the history of economic thought that over investment through highly leveraged borrowing under elastic credit supply may generate large boom-bust business cycles. This paper rationalizes this idea in a dynamic general equilibrium model with infinitely lived rational agents. It shows that dynamic interactions between strong asset-accumulation motives (based on habit formation on the borrower side) and elastic credit supply (based on collateralized lending on the lender side) generate a multiplier-accelerator mechanism that can transform a one-time technological innovation into large and long-lasting boom-bust cycles. Such cycles share many features in common to investment bubbles observed in the history (such as the IT bubble in the 1990s and the 2000s housing bubble.).