OK, OP, your brain only reached maturity ( from evolving into maturity, therefore, it' was NOT mature before 25).
You only have 30 years until you are old.. from how I understand your post...
I do wonder, then, when you are 60, whether your mindset will allow you to retain some sense of esteem. And if you are physically able, whether you will have a sense of self-worth?
You may have grandchildren, or may not, do I understand the spirit of your post to mean that the best of life, and one's life's worth, is therfore now gone?
I do understand the effect of time passing on one's own perception of life and mortality, but, for me, and I suspect many others, in their 60's, 70' and 80's, life is as precious and valued by oneself and their loved ones, as it ever was. We simply move into different roles.