I first found out I was an “Old” (as opposed to just old) in 2012 when I started working for BuzzFeed as an “ad critic.” At 52, I was by far BuzzFeed’s oldest employee. The under-30 editors there used “The Olds” or “Olds” internally (sometimes even in posts) as shorthand for anybody above the age of their demographic target, people who just didn’t “get” it.
I also found out that the term was used by millennials nationwide, not just at bleeding edge New York City social media websites. Before millennials came along, though, “The Olds” was (and still is) a group of old American whiskeys and bourbons (Old Grand-Dad, etc.).