An older leader often has fewer long term stakes in the decisions they make, if they were to destabilize the economy or lead the country into conflict, they may not experience the full consequences of their actions, as their personal future is less affected compared to younger generations. Leadership at that level requires making decisions that will shape the long term future of a nation, and it’s crucial that those in power have a vested interest in that future. Additionally, presidents and politicians are public servants, and like any profession, there should be an age limit or retirement age to ensure the vitality, adaptability, and long term accountability necessary for effective leadership. At what age do you think they need to retire?
The thing is, this is imo the most problematic problem of democracy. It is also not an age thing.
Political leaders normally don’t stay long in any specific office. E.g. most finance ministers are just finance ministers for a few years. If they survive one term that is long. During the term they are oftentimes planning their follow up career in the private sector. This can takes up more of their efforts than national politics.
It is even worse in local politics. Many mayors of large cities are already planning their career in national politics. They don’t care about what happens to the city once they switched over.
So, I wouldn’t limit myself to “old politicians”, because they might die before seeing the consequences of their fuck ups. Young politicians also almost never see consequences for their fuck ups, because they will have moved on before it gets problematic. The politicians know that!
This is a much larger problem than your question let it seem to be, it is imo the biggest problem democracy in itself inherently has.
Rule limits actually make this worse, because it leads to short term thinking. But not having a rule limit is also not an option as it opens up roads to autocratic behaviour.
I work in local infrasrtructure management now and worked in science before. I despice politicians, be they young or old. We administrators are constantly fighting them to keep our city/country livable (and we lose more than we win).