Why can’t millennials afford their own homes? Reading much of the popular press, one is led to believe it’s their unrealistic expectations, indulgent spending, and general allergy to adulthood that have trapped them in a renter’s purgatory. Nebraska senator Ben Sasse wrote a whole book, The Vanishing American Adult, in which he argued that young people today are stuck in a Peter Pan–like state of carefree childhood, spending their time playing video games, buying stuff, and snapping selfies—e...