WIRED: "We may be trained to think that the new is about to overcome the old, but that’s just an optical illusion. Because the failure rate of the new is much, much higher than the failure rate of the old. When you see a young child and an old adult, you can be confident that the younger will likely survive the elder.
Yet with something nonperishable like a technology, that’s not the case.
There are two possibilities: Either both are expected to have the same additional life expectancy, or the old is expected to have a longer expectancy than the young. In this situation, if the old is 80 and the young is 10, the elder is expected to live eight times as long as the younger one."