Yet another +1 on this: I worked at the same tiny shop (a partnership-like handful of people) for about 15 years; We navigated a few technological transitions throughout those years and made more money than we probably should have, but when I (at age 40+) found myself at a larger shop, learning the latest tech stacks was definitely not the biggest challenge. Indeed, the challenge was slowing down a bit, submitting thoughtful PRs, coordinating with designers, writing documentation... you know, actual engineering process. I got my hands smacked mightily a few times at first, and I got PRs rejected, but I got the hang of it. And yes, my long-dormant telephone magically started ringing again as the technologies, people, and companies on my Linked profile started catching recruiters' eyes again like they did back in the day. It can happen to anyone, but I can see how it'd be particular common among people over 40. After all, I spent my entire 30s with the attitude of "this is working and making plenty of cash, why change it?"