> Those buying new don't care about repairs.
Yes because thy live in the John Deere future. This was not always the case, surely. You used to be able to take high school classes to learn how to fix a combustion engine, even a new one!
You still can. My 26-year-old took automotive shop when he was a Junior in HS. Of course, we live in a rural school district...
Keep in mind that tractors are also getting massive.
The economics of row-crop agriculture is "you gotta farm more land". That means spending as much time in the field as you can with as big a machine as you can.
So not only is time you spend fixing your tractor yourself time you're not spending on your primary job, it's also working on a machine that's just monstrously huge. Delegating that work to a specialist with specialized tools is a very reasonable way to live.