These "people you know" - if they have those conditions and are yet unhappy are obviously mentally ill. I know NO-ONE - who has all such conditions fulfilled and is yet unhappy. I cannot conceive of such a person. I suppose that is what neuroticism means - havven't experienced it, but yes, I can imagine some folks are like that. Sad really.
And hey, people who posit the existence of "God" and other such unverifiables have no right to demand objective proof of anything.
Define for me the objectively verifiable -- that is, observable and measurable -- characteristics that define "flourishing."
I won't hold my breath.