The housing bubble was entirely speculative. It was stoked by the fed keeping rates low, later fear took over as people didn't want to be either 'priced out forever' or miss out on easy money.
As others have mentioned it's apples and oranges, you can not sell nor live in a degree; defaulting on your student loan will not render you homeless. The bubble and collapse in house prices is far more signigicant to the larger economy. The housing market is measured in trillions, student loans in billions.
Don't get me wrong tuition is way overpriced for what you get. A drop in tuition and house prices would do everyone good.