> I do believe you can change yourself.
I don't believe you can change much. You can force yourself to behave differently, but at a cost of extra effort and suffering.
Instead of personality change, I think the environment changes, and we express different psychological features depending on the situation. There are people/situations that bring out the best in us, and the opposite. Who we are depends on where we are, and with who we are interacting.
And of course with more experience comes less over-confidence. We change our values in light of our past experience.
Another thing is risk. The more you have to lose the less you want to risk it. When you have invested a lot in a family or career, you change your values in order to minimise risk.
So I think we are not changing our personality but it reflects differently because our situation has changed.
This realisation helped me forgive myself of the torture of changing my personality, instead I seek a situation where the better characteristics of my personality shine. I have always been myself even though externally I changed.