An interesting point of view. Practically, I agree with you, that FU wealth is probably the most realistic way to achieve the freedom required for some personality types to achieve happiness.
I am unfortunately one of them, intellectually, I've conclude the same for myself many times over, and have been unable to change my view on this, as much as I'd love to find peace in my sitaution and enjoy life (tm).
What's hard about it is that it's probably impossible for most people to achieve this kind of wealth, after all, in the current socioeconomic situation, you can't be rich in any traditional sense of the word, without someone else being relatively less well off.
Until we have robots doing our work, and almost-infinite access to resources through no or little work of our own, the traditional definitions are valid.