Earlier quoted context omitted.
Assuming risk is evenly distributed between birth and death, you would expect a 1 in 80 chance of dying in any given year. But since the risk is loaded towards the later years of life, 1 in 200 during the earlier years sounds about right. Perhaps it's 2x higher than I would have guessed otherwise, but it's the right order of magnitude.
No that is bad math around 1/80. If the average person had a 1/80 chance to die each year, the average life expectancy would be 40 years. Think about this another way. You have a gun with 80 chambers and 1 bullet. How many times on average can you point it at your head and pull the trigger before it goes off? Would you still argue 80 times? On average it is the last chamber?
E = p/(1-p)
So pretty close to 80 years, no?
I guess it gets more complicated because you'd die of other reasons as you age so there's no point including the eventualities where you reached 120 for example... I guess it gets pretty complicated in the end...