I am nearing myself my mid fifties. I want to say to you that those times when you were younger and also poorer in terms of materials, those were still beautiful times because you can compensate a lot in younger years for what you might miss on the success or material side of life.
Becoming old and older though gives you entitlement for saying "been there and done that" and also to slowly but surely changing the sides from being told what to do, to say, to think and to act, and all the doubts which somewhat determine the first half of life, to the other side. This happens gradually.
Having self doubts is precious, though, only the insane does lack them. I know that becoming old gives a dignity I was not possessing before, while I must say that it's hard to say good bye to the sassiness of my young adult years. I feel it does not fit me any longer. So you exchange one for the other.
Today I am way better off financially than I ever was. I can say that no money or wealth whatsoever can replace personal serenity, luck and relations.
I once had a severe crisis though. I think modern people have them more often during their adult years since they don't enter adolesense through proper maturity trials which are honored by their peoples at their puberty. In a way we "civilized" peoples are cursed to endure these crisis more often than it was with tribes people who could be sure to be welcomed in the world of the adults after they passed their tests early on.
RE: QUARTER-LIFE CRISIS.