But he's not like the overwhelming majority of suburban homeowners; he owns mansions.

You'd actually think that a multibillionaire who owns a mansion would be less sensitive to fluctuations in home values, since their wealth is usually contained in other assets (unlike the average American homeowner, for whom their home is likely where the majority of their net worth is). If Andreessen were to accidentally light $200M of his own cash on fire, he'd come through it, lifestyle unscathed.

Where I live, property is expensive, and I live in a neighbourhood that seems to be dominated by investment property; many empty properties or short-let properties. There are no kids here, even though the neighbourhood would be fine for kids.

Anyway, that's apparently not the way the cookie crumbles; owning property so you can live in it seems to have become unfashionable. I hope the fashion changes, because I have no plans to sell.