It’s a normal thing our brains do if we’re lucky enough to live that long.
Humans didn’t evolve to live in such fast pace worlds. So if someone made it to 60, running on “autopilot” wasn’t as big of a deal. So as we lose critical thinking skills (again, completely normal) we fall back on stuff we learned as kids and stereotypes to be able to keep up.
It’s why not having an age limit on elected representives is so crazy.
It’s outright denial of science to pretend an 80 year old is still capable of leading a country. For more reasons than just that one.