What a wealthy person wants isn't necessarily greed, and we need to stop thinking like that. Even in Roman times, wealthy got together to fund various projects for the greater good.
What the wealthy want most of all, is if you take their wealth, that it truly does go towards a greater good. And "building more houses" takes wealth through free-market capitalist systems in any case (ie: its not a direct wealth taking we're talking about, but a steady change as zoning laws allow more houses to be built).
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Most of these "wealthy retirees" are looking aghast at their children's opportunities. My brother-in-law's parents may own 3 houses, but they were complaining to me about their daughter's inability to find a house in this current market.
They care far, far more about their daughter finding a good house and starting her family, than the value of their 3 houses. And I bet many, many, many other families are in the same situation. (Rich/Wealthy retirees scared for their children / grandchildren).