The other faulty reasoning here is that living without roommates is a reasonable expectation for most single, urban twentysomethings. Most engineers I know have

The other faulty reasoning here is that living without roommates is a reasonable expectation for most single, urban twentysomethings. Most engineers I know have roommates as much for social reasons as economic reasons. If you take most of those two bedroom rents and look at the cost per month per room, most are less than 30% of after-tax income. (And that's if you choose to live in SOMA, which also seems like an extravagant and uncommon choice for most engineers I know, many of whom are happy with a short commute to the Mission, Pacific Heights, or Oakland.)