I think one important consideration missing from this discussion is electrical problems. If your vehicle has an intermittent electrical issue as a result of grounding or bad wiring or a design defect, it could take significant time to diagnose and you may end up spending thousands of dollars.
As an example, I had a car that was only about 10 years old but had an issue with intermittent brake lights. Brake lights would turn on while driving and sometimes turn off when braking. There were other minor electrical problems, but obviously the brakes were a safety issue and after spending money to attempt the repair three times with different technicians (including a dealer) it left me without many options. Mechanically the car was fine, it only had around 120k miles on it and I really wanted another 5+ years out of it.
Not an option IMHO.
Following a trade-in on the vehicle, about a year later the manufacturer issued a recall and admitted that there was a defect in the engineering of the braking system. I guess if I had waited another year it would have been possible to finally get this thing fixed, but was that worth risking my safety on the road where other drivers never knew if I was braking or not braking?