Oh I agree! But the idea of wealth concentration that then tapers out as a function of distance from the city center bears at least a superficial resemblance.

Oh I agree! But the idea of wealth concentration that then tapers out as a function of distance from the city center bears at least a superficial resemblance. Perhaps why one works and the other doesn't is that personal wealth accumulation IS like water: it'll get stuck in local maxima, etc - whereas city wealth accumulation is more like sand; as it piles on top you get landslides that distribute.