How do they buy anything else, like textbooks or coffee? They have a student loan - that's how.
You ever met a college student with an Xbox? If we stopped treating houses as an investment and started treating them as a commodity like Xboxes, you could afford one.
I very much doubt it because it takes many times as many resources to create a house than an Xbox. Making housing loans to people with no income or assets is a great way to cause a financial collapse, as we saw not too many years ago.