Given his determination to swing a socialist wrecking ball at our national economy, it’s no surprise that Bernie Sanders also embraces destructive policies at the local level.  He’s a NIMBY (for “Not In My Back Yard”), recently declaring his opposition to constructing 10,000 badly-needed housing units on a defunct race track in East Boston, tweeting that “we need affordable housing for all instead of more gentrifying luxury developments for the few.”

Of course, claiming to serve the interests of the poor while protecting one’s own is a commonplace.  Locally, in D.C.’s Ward 3 – its wealthiest – residents have delayed or stopped a proposed apartment building and organic market.  In investment-starved Baltimore City, the well-heeled residents of Roland Park recently won a lengthy court battle preventing construction of 148 new apartments.

I’ve seen how this works out in the long run, and it’s not pretty.  In California, my mother-in-law was a dedicated NIMBY.  She often complained that, thanks to rising home prices, her kids might not be able to afford to live in the Golden State.  But if anyone proposed building anything – especially higher-density housing – in her sprawling suburb, she would join her neighbors in protests against it.

This led to interesting discussions with her insensitive son-in-law, who would say things like “can’t have it both ways, mom.  It’s supply and demand:  you limit supply, and your kids pay through the nose on their rent or mortgage – or they just move away.”  Which provoked lengthy rebuttals, during which “loss of green space,” “traffic congestion,” and “preserving quality of life” got prominent mention.

Ultimately, California’s NIMBYs won that debate.  Since 1990, the state has allowed construction of only one-third as many homes (on a per-capita basis) as it did in the previous three decades.  It now ranks last in the U.S. in homes-per-household, which therefore have a median price (over $550k) that is more than twice the national average and second-highest in the country (behind only Hawaii).  These days, half of my mother-in-law’s offspring live elsewhere and only one of seven grandchildren remains in California; he lives with two apartment-mates and has a hellish 1.5-hour-each-way commute between his job and affordable housing.

Indeed, Cali is strong evidence that NIMBYism is not, in fact, a quality-of-life-preserver.  Clearly, high housing costs are not the sole or maybe even the primary reason for homelessness, but it’s a contributing factor – and it is no coincidence that half the nation’s homeless are on California’s streets.  As its middle-class migrates out, the state now has greater income inequality than Mexico and the highest poverty rate (adjusted for living costs) in the country.

But those long-ago debates with my mother-in-law have taught me that changing NIMBY minds is a heavy lift.  The problem is not merely a fondness for “open space” and a wish that there should never be any cars on the road but yours.  There’s also financial self-interest:  if you already have your house, limiting the supply of new ones puts money in your pocket.  Extra equity, no sweat.  No surprise, then, that California’s senate recently rejected a bill that would have allowed for “upzoning” and creation of higher-density housing near mass transit – the bill’s third failure in as many years.

Fortunately, however, those marginalized by NIMBYism are mounting a counter-attack.  Meet the YIMBYs:  starting with some angry millennials who grasped that reflexively limiting housing supply can shut them out of the American Dream, the “Yes In My Back Yard” movement has been gathering adherents – even in Cali.

And YIMBYs are on the right side of history.  Care about climate change?  When it comes to our carbon footprint, density is good and sprawl is bad; upzoning is green.  Care about affordable housing?  Just build, baby.  It’s more effective to add housing supply – of any kind – than it is to tax developers with “inclusionary zoning” mandates aimed at subsidizing below-market units.  Those new East Boston, D.C., or Baltimore units may or may not be “luxury,” but their new tenants would open up vacancies in slightly less luxurious digs, and their new occupants would have vacated still lower-priced opportunities for others, and so on.  Average rents move downward whenever and however supply expands relative to demand.

So it’s past time to take on the NIMBYs and call them out.  Even if they don’t see how being a YIMBY can help save the planet or treat homelessness, maybe they’ll just want to keep their grandkids close.

Stephen J.K. Walters is the author of Boom Towns: Restoring the Urban American Dream and is chief economist at the Maryland Public Policy Institute. Email him at swalters@mdpolicy.org.