The president is a very special role that requires a lot of stamina. It’s also a role where there’s only one in the whole country. The travel schedule alone is extremely difficult.

If there is only one role to fill it’s logical to be selective. Why hire an 80 year old when there are a dozen qualified 50 year olds who are physically better equipped to handle the rigors of the job?

The president is the commander in chief of the military. The military forces retirement at a certain age, why don’t we do that for the president?

Let’s not forget that the American president is a massive presence as a global figure that impacts the whole world. If they die in office, get ill, misspeak, etc, it negatively impacts the entire nation if not the world.

Biden accidentally calling Zelensky “Putin” in public was an example of something that could have been a disastrous foreign relations blunder if Zelensky or other allies to Ukraine were less understanding and took offense.