Interesting premise for some philosophical musings, but terribly unrealistic. In fact, I think the first assumption is easier to achieve than the second.
Plus, of course the physical limitation that no one can ever be rich enough to share endlessly.
Then the super-rich will start sharing their wealth, because if they don't, their competitors will do it first and take all the fame. It is not from the benevolence of the super-rich, the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest.
I don't think I'll be holding my breath waiting for ultra rich to be motivated by fame of this type. In fact, I think it's wishful thinking in its finest form.
They live a post-scarcity life, but not everyone does -- or can (probably, still). Once everyone could, the greedy hoarder mentality they (and pretty much all of us) operate under right now might (hopefully?) come to be seen as pathological, not ideal.
The whole point of money is lubrication under scarcity. If you don't have a job, you don't have money. No lubrication.
So no difference from current conditions, then, except the objectively better quality of life.