I've seen people like that, and I've been that guy. Ironically, I've been that guy only because I left years after those other men and women that I'd looked up to had moved on, and I'd filled their role for the junior devs who were hired after.

Moving on is a fact of life, more so now that ever. My parents both worked for the same company over 35-40 years before they retired; I don't think I can imagine that'll be even close to the norm for many in the workforce now (especially software / other tech).