Your reasoning?
A person under age 35 cannot become President as our Founders considered that a good age wherein the person would have accrued enough maturity and experience to govern a country.
But conversely, does not the risk for age related diseases such as dementia and cardiovascular disease rise with extreme age?
Why risk a potentially mentally or physically compromised President? I think we've had enough Presidents die in office. We also did not do very well in the last two years of Wilson's term when he was too mentally disabled to govern effectively.
Also, as noted, every single time we have had an aged President there has been some issue, especially in their second term. If Eisenhower's heart attack or stroke weren't as mild, we would've had a President Nixon in 1957. There is an open question of Reagan's mental acuity in his second term.