You would easily be able to predict Button's death

If Benjamin Button grows up to look like a 10 year old, and then an 8 year old, then 5, then a toddler, then a baby..well you would know exactly how long he has left. Babies don't stay babies for long at all, yet old people can just get older and older and older, and some old people die at 80 and some can go on for 20 more years! So basically Benjamin's death was already specifically planned right from his birth, unless something else killed him first.