I agree with every word of this. I would also add that there's a third category, or maybe a 2.b: individual contributors in their 30s and 40s who look ahead to their future and say "well, I guess I better become a manager at some point" without having any particular aptitude or even an intrinsic desire.
Many organizations have quite intelligently created parallel paths for contributors to keep advancing, which somewhat mitigates this effect. However, in the past, this was a widespread phenomenon, and it's still out there to some extent. You find contributors who think management is easier, or more prestigious, or less prone to ageism, and so will switch tracks.
I think this kind of thinking highly depends on what field you are in.
My father worked in a technical role all his live in a automotive plant. (Eventually being technically responsible for overall design and implementation of all production lines).
A lot of his former collegues moved into management during the early 2000's. Most got fired after the great recession because being a manager is considered a non skill compared to actually contributing to the actual core bussiness.
I would argue being responsible for a major operational part of the business is far more prestigious then being a manager.
I have a startup of 3 growing up to 15, and I have this awesome
opportunity of hiring a career manager who’s sensible and everything. But he can’t code.
I’ve erred for a month, but I just told him no. I still wonder whether I’m in the “worst managers reject good managers” category or in the “you gotta belong to the people you manage” category. But being able to do is very high on my list.
To have a large impact in most orgs, one often needs to directly influence how other people work. In software, the leverage might come from technical output instead.
This might be a deeper reason why moving into management is often necessary for most orgs. Exceptions include software-focused organizations where code can be one's channel for impact.
it is a very real fear. When you look around and realize everyone that works at a company that is over 60 is in upper management it becomes clear that you either move up or out. I have also noticed it is sometimes hard to keep up with certain types of work after a certain age. The strength you retain as you get older is wisdom of experience.
Many organizations have quite intelligently created parallel paths for contributors to keep advancing, which somewhat mitigates this effect. However, in the past, this was a widespread phenomenon, and it's still out there to some extent. You find contributors who think management is easier, or more prestigious, or less prone to ageism, and so will switch tracks.