Not disagreeing (edit: well maybe I am, a bit) but with a Tesla the "upgrade" is pretty much mandatory as the battery packs have a limited life. So even if you don't need to upgrade to get the extended range, you still need to replace the battery pack every so often. Also other components on the car will wear: brakes, suspension, interior. A lot of people trade/replace cars even if the car is still running and reliable, just because they are tired of them, the interior is worn or falling part, the seat springs are flat, etc. Or they just want something different, bigger, or with different utility.

You could take most cars of the last couple of decades, and a complete interior update, engine/transmission replacement, and suspension rebuild would still be cheaper than a new car. But few people do that.