Mileage

As someone, who never buyes a new car, because I don't like that first huge bit of deprication I don't understand why so many people take that, but shy away to do some miles with their car.
For example, you buy a new 550, drive it ten years but watch to never corss 30k miles cause there is a huge service waiting and prices my drop 20k (something I read in this subforum)

For me, this is preserving the car for the next owner. A 90k 550 would command now 20k to 30k less. But someone sparing the car for that money would have wasted up to two thirds of the cars original value (which is much more money) for watching the car in his garage?