That is the reason I love gear heads, otherwise I wouldn't have been abke to get the Nikkor lenses I have for the price I paid, and they are all used by the way. That none of those is compatible with the new Z system helps as well.
Because why would a camera and a lense, that was the top of the line back the day, be less suitable today? Not that a Z9 wouldn't be nice, but I have other hobbies as well and want to see places!
I've never bought flagship gear, and I often buy second hand. This is the way.