My comment is pointing out that people often have room mates, and always have often had room mates. Especially in high cost of living areas. Especially if they are young. Even if they have high paying jobs. A friend of mine is a quite experienced physician, and I've known her for a couple decades. She had room mates as an internist, and for awhile afterwards. It made financial sense.

If your argument is that a meaningful number of people who historically would not have had room mates, now do, not because of a different set of choices they are choosing to make, but rather due to economic situations requiring radically different choices then maybe some data would be useful?

I know a lot of people who are clearly choosing to live in a city who probably don't need to. I know of many people choosing to have room mates because of economics, but would historically likely have made other choices (cohabitating with a boyfriend/girlfriend, moving to a different location, getting a different job, etc.).