It depends on what part of the industry we’re talking about. One aspect of this is startup culture and needing to “fit in.” Or in other words “culture fit.” You see it on HN all the time where people mention many of their friends are coworkers. Sometimes that means not hiring the person who has a life outside work, isn’t going through the same issues everyone does in their 20s, and is perceived to not fit in. In some cases, I think it is simply the threat of possibly having a life outside of work and not signing up to overwork yourself by default.

Another is pricing yourself out of the industry. And another is the mistaken idea that all an older dev knows is older out of date technology. The usual stuff.

I’ve found that firmware and regulated industries in general do not have as rampant of an ageism issue.