I would not say "might" but "will". Eventually the car becomes more expensive to maintain than to replace. But that is not some terrible thing to avoid, it's just a recognition that the car has a finite life you need to estimate when making your purchasing decision, so those maintenance costs are fairly shared by the seller and buyer, with the seller paying half the future maintenance forward in the form of depreciation and the buyer agreeing to take on the other half in exchange for a cheaper car.