Too close to the best by date
I work for myself, but I keep an eye on the job market and put in an application from time to time if I see a position that might be a good fit. What I typically find is big tanks full of ageism. Do these companies think that an older worker isn't going to be around for very long? Younger workers tend to hop jobs more often as they don't have kids to support or a home with a mortgage. They may also not have older family members that they want to remain close to so they can be looked after. The downside with an older worker is they won't take abuse as readily. I know I won't. The upside is that I have made or seen or contemplated any number of mistakes already that I'm not going to repeat. I also don't take as much personally which means I don't blow up at colleagues, customers or vendors. I just solve the problem and move on.
With my qualifications and experience, I should be getting at least a polite rejection letter, but HR departments don't even bother these days. Some years ago I did get an invitation to interview about 6 months after I sent in an application. I replied that they must be joking, I was long past wanting that job.
I agree with several posters that often times it can be up or out. I may or may not want a management post. It would depend on the job and the company. I may be perfectly happy keeping the same job with a pay rate that keeps up with inflation. I might also be more than willing to take a lesser job than my qualifications would point to if it was interesting work. That can be the case for people looking to switch industries.
Biting the hand that feeds IT
