No one would be forcing them to move.<p>Now some might _choose_ to move because they could sell their single-family home for a much higher price to someone who would then build a multifamily building on the lot.  But that&#x27;s obviously their business.<p>But to the main point of your argument, about happiness: it&#x27;s a general truism that people in low-density-zoned areas are happy there and oppose any sort of upzoning anywhere nearby.  Upzoning nearby but not on their actual lot is particularly bad, because it would reduce the value of their real estate; people fight _that_ tooth and nail.<p>The result is that everyone who is already there is fine; it&#x27;s people who are trying to enter the market, either via moving to the area or by growing up and trying to move out of their parents&#x27; house, who get screwed.  But since by and large those people don&#x27;t vote (the young for demographic reasons; the not-yet-residents because they&#x27;re not yet residents), it&#x27;s the incument residents who get to control the zoning rules to their exclusive (perceived, at least) benefit.<p>Which is all fine, but then prices get out of hand and people panic and start introducing things like rent control and whatnot, which makes prices get even more out of hand anytime someone actually moves.  And then we see the current San Francisco real estate market.