Why do we get more conservative (little ‘c’) as we get older? Trying out new things pays off less when there’s less time left to benefit from the upside. That’s a simple story based on declining patience.
But there’s another reason which could kick in at middle age when there is still plenty of life left to live. Think of life as a sequence of gambles presented to you. They come with labels: gamble A, gamble B, …, etc. Every time you get the chance to try gamble A its a draw from the same distribution and you get more information about gamble A.
Suppose your memory is limited. What you can remember is some list of gambles that you currently believe are worth taking. When you have the opportunity to take a gamble that is on the list, you take it. When you are presented with a gamble that is not on the list you have a decision to make. You could try it, and if it looks good you can put it on your list but then you have to drop something else from your list. Or you can pass.
As time goes on, even though you don’t remember everything you once tried and then removed from your list, you know that there must have been a lot of those. And so when you are presented with an option that is truly new, you have no way of knowing that and your best guess is that you have actually tried it before and discarded it. So you pass.