Simply make student loans dischargeable in bankruptcy. Right now there's no countervailing force to taking out as large a loan as possible when you're 18 except

Simply make student loans dischargeable in bankruptcy. Right now there's no countervailing force to taking out as large a loan as possible when you're 18 except your ability to anticipate what your life will be like ten years from now, which is difficult for most people and particularly difficult for teenagers. Making lenders have some actual skin in the game will make them perform due diligence, and the market will quickly correct itself once they have to bear some of the risk of a degree being economically worthless.