There are post-scarcity examples in human history (see gift economies and potlach societies - common among native americans and in the pacific islands) where social pressure caused any accumulation of wealth to be shared with the entire society (this is a bit similar to Andrew Carnegie's dictum that to die rich is to die disgraced, now leading to the billionaire's pledge). Of course, this only worked because the societies were individual tribes/villages and fit within Dunbar's number, where every individual knew every other individual in the society.

If post-scarcity is brought about by automation, then there will be no need for most people to work, and socialism won't be the appropriate economic model (since people will not be directly involved in production). At this point we'll probably need to return to a gift-like economy.