Lu,
You mentioned " Lets address a typical long haul jet that flies 3500 hours per year and there are 100 in the fleet. It would take 2,857 years to accumulate one billion hours. Can you visualize any mechanical or electrical system lasting that long or longer prior to catastrophic failure? "
Everything eventually 'wears out'; be it people, planes, pyramids or planets. It's just a mater of time.
I don't believe that, when discussing statistics and probability, it is correct to equate [1000 items lasting 1000 hours each] with [1 item lasting 1,000,000 hours]. Would you agree?