> you will eventually end up with a set of tech skills that a kid 20 years younger than you, with no family and so being able to live on lower salary, probably has too.

I was this young hotshot 20 years ago. In hindsight, the skills I had at the time were commodity or even irrelevant compared to the wisdom, life experience, and maturity that took me 20 years to develop and determine how effective I am now. You can't fake or rush those 20 years. (Even though the me of 15 or even 10 years ago wouldn't believe that statement.)

So I agree, although it wasn't really managerial skills that became important for me. It feels more intangible. I got sort of lucky that I didn't have to transition into management as I got older.

But that's not to say that many workplaces won't value the young hotshot anyway. I'm retired but if I was job searching I wouldn't really consider myself in competition with them, I'm not looking for the positions that can be done as effectively by a 28 year old. That's not a matter of job title or seniority, it's matter of finding people and positions that value or need the more subtle strengths that I find most valuable and important and interesting about myself.