Allens dream is impossible. Humanity is a naturally greedy species that can never feel content. Its simultaneously our greatest strength and weakness. Strength in that our never ending want for more is what has driven us to seek out new things and innovate. Yet weakness that we can never be satisfied and thus will always seek more, no matter the damage and cost.The trick, ideally, would be to ensure that those at "the bottom" are still able to not only live, but flourish with dignity. The 'stable boy' wouldn't want for a warm, dry bed and always having food on their table, and help when they're hurt or sick.
That's what I take from Allen's vision, at least. Not that everyone is rich and a king and tied for 1st place, but that those at the bottom of society still live fulfilling lives and are free of oppression and discrimination, and those at the top be morally upright and don't seek to control and oppress those beneath them.
Which....is possible, but at-scale is arguably very difficult to enforce at a sufficiently large society, without a lot of governmental-type levers to discourage runaway greed or malice while balancing against personal liberty and the common good.
And of course, setting something like that up takes a lot of work and time and buy-in from everyone involved, and I do not know if Allen has properly reckoned with that fact.
To fundamentally alter that is not possible and if it was. The world would stagnate and fall into collapse.