Experience

 An interesting aspect of experience is that when you have little of it many issues arise that can seem traumatic.  As you gain more experience you begin to realize that many issues are survivable and thus become less traumatic.  As you age you generally accumulate a lot of experience and many issues that might of been traumatic are less so.  This is an aspect of wisdom.  

In contrast though, when you have a great deal of experience and you encounter an unfamiliar issue then it can be just as traumatic as if you'd encountered it at an earlier age.  This may help to explain the peculiar risk aversion as you get older.  In a sense, it's a reluctance to gain further experience. This may be an aspect of your brain filling up.  Your mental capacity begins to roll off at around age 30.  Whether or not it declines is an open question, but the amount of free space likely dimishes just because it gets consumed by experience.