A tech CEO in his mid-fifties once told me: "There is no ageism in the valley - by the time you get to your forties and fifties, you are either a CTO, or you weren't very good to begin with".
By definition, there will always be less numbers of managers than technicians.
Being a manager is a different skillset and not everyone WANTS to be a manager.
Typical comment from a clueless pointy haired boss!