I'm about ten years older than these fellas who are expressing concerns and can confirm that your comments hit the nail on the head. I don't find the camera intimidating because I feel that Ii wouldn't sweat it. yah, there's a learning curve, but the d850 is a complex camera too.
you don't need to know how to do EVERYTHING to operate it. you can get the basics down and expand as you go.
quite frankly after a couple of years of owning the z9, there's a ton of stuff i would have to go look up to figure out how to do, but the realty is, i don't need to because they're things i don't need to change or use.
when i first got my d500, i literally couldn't get an image in focus for DAYS. i, too, feared i had made a terrible mistake. it turned out to be something dumb, i don't even remember what, but i went on to love that camera and i used the heck out of it for many years.
should be concerned only about the features I am going to use regularly and learn the other shortcuts and features as I need them. It is just a simple progression: learn, practice, execute and move on.
Trying to learn everything at once is like trying to drink from a fire hose, but learning at a pace that supports what you are trying to do is not a problem. Practice and learn to understand what the functions do (and why) and it becomes much easier to remember what, and when to do it. Most of all DO NOT become intimidated by the camera.---it is merely a tool and you are its master, though it is certainly can be a complicated tool. You made a wise choice in purchasing this camera so apply the same judgement and attitude towards learning to operate it. Like John Navitsky said above, there is nothing wrong with going back and refreshing your memory on what you've already learned if you are not using that feature often.
It's fun to learn new things so pls approach learning the Z8 as a fun project and enjoy the ride.