Well, he is actually 77. Ike left at 70, Reagan 77.
Fair point though. He is old so there is a risk he could drop dead from 2024-2028, at 81/82. Healthy lifestyle of no booze or drugs does not guarantees a longer life span. The enormous stress he is under, could just as easily any erase any benefits for longer life expectancy from a relatively healthy life free from alcohol and narcotics.