Subsidized housing doesn't prevent gentrification, it just shifts rental profits from landlords to subletters, while depriving the city of tax income on the market value of the housing.
> Gentrification is a real social concern
Why? Why is it that nobody bemaons the pricing of gucci watches or belgian caviar or first class airline seats, but as soon as it's "living in one of the most desirable neighboods in the world", all reason has to go out the window? Clearly not everyone who wants to live in San Francisco can live in San Francisco, why aren't we talking about the millions of people in (for example) Somalia who are being prevented from moving to Mission Hill by gentrification? Why is it just those who by accident of history decided to rent (which by it's very nature is temporary occupancy) in SF that need to be now subsidized?
Because the sale of Gucci watches does not push more affordable watches off the marketplace and out of the hands of people who do not have enough money for more.
The issue with gentrification is this: it ruins existing communities and takes opportunities away from people that don't have many to begin with.
People have to move from the neighbourhood they've known for decades with good facilities and schools to an area considerably further away from the job market, bringing down their quality of life and reducing the chances that they'll ever be prosperous enough to live in the neighbourhood they've just been forced out of. But hey, smart, innovative kids will still rise up, right? Well, no, because now they're nowhere near the good schools and after school programs. Neither they nor their parents have the opportunities that others do. It's not exactly the kind of meritocracy Silicon Valley champions.
The very fact that you think these people are deciding to rent speaks volumes. Not everyone can afford to buy a house or get approved for a mortgage. They have to rent, and are increasingly powerless to stop these kind of changes. Gentrification is not all negatives, but are you seriously saying you can't see why people would be angry about it?
We also have other ways. San Francisco's rent control is one such way. It entitles the tenant to continued occupancy and limits the rent the owner can charge that tenant. Of course, this has significant negative side effects. It deliberately fails to respect the owner's interests, instead rejecting him as an invalid actor, some sort of Evil Capitalist type. It effectively functions as a wealth transfer from the owner to the renter, in the form of foregone rent increases. This naturally changes the capitalist's incentives, inhibiting the maintenance of and formation of new capital (specifically the capital we call a "housing stock"), and provides other perverse incentives for the landlord to mess with tenants.
In the case of San Francisco, this housing shortfall exacerbates its problems by raising the price of all housing... a humanitarian tragedy far in excess of mere neighborhood-dissolution. Not that this is the only thing that inhibits homebuilding in the Bay Area, though.
SF does not have an abundance of good public schools. It's not atypical for families with school-aged children to move to the suburbs to afford their children a decent education.
> ...to an area considerably further away from the job market
But it's the techies with the disposable income who are creating a significant amount of the jobs the blue collar workers seek. The benefits from having people with disposable income is not extricable from the people themselves. Else you can have Detroit. That's the end-game.
I don't know of there being a 'right' to live in a particular place. Such that I would have a 'right' to live in Berkeley --whether I could afford it or not. Or Oslo, or London.
Why don't we see people clamoring against the 1%-er actors and actresses in Hollywood? I think people in LA understand that these free spenders benefit the local economy when they spend their money like there is no tomorrow. If the overwealthy actors and actresses in Hollywood didn't spend their monies, then that _would_ be a problem. There's be no infusion into the local economy.
Another way to think about it is this: If you believe in the free market and it's ability to find the "right" price for everything, even the abstract (e.g. the time value of money), then how can you support a government enforced system that allows a finite amount of money to purchase an infinite amount of something, which is what ownership of land in perpetuity amounts to. Property taxes are a weak proxy for the time value of land, and is not determined by the free market. If we want a true free market, all land should belong to the commons, and we have a free market of long term leases. The proceeds go to the community pot (e.g. pay for government services, or checks sent to every person). Gentrification thus costs the gentrifiers and pays those who lose out. Please read the above link and understand the arguments before responding to my claims in this paragraph.
I'm not a "real" libertarian; I am neither a child nor a sociopath.
> If we want a true free market, all land should belong to the commons, and we have a free market of long term leases. The proceeds go to the community pot (e.g. pay for government services, or checks sent to every person). Gentrification thus costs the gentrifiers and pays those who lose out
I'm fine with that. Seriously. I'd even send checks to the poor bastards in Somolia. I mean it's a shitty world where I make a lifetime of money every month because I was born white, male, American, and am autistically brilliant at telling comptuers what to do, while other people die of malnutrion.
What I have a MAJOR problem with, is people who rent in San Francisco, and thus insulated themselves from real-estate downside risks, but now that upside risks are impacting them, want bailouts. "But I'm special, I live in San Francisco, I'm a unique snowflake that deserves to pay only $600/mo for a $2,600/mo apartment because eveyone else is so rich and I'm so poor and lattes are so expensive!"
(And yes, I do donate to charity, and I don't write that money off on my taxes, as I don' think that charity should displace the obligation of a government toward its citizens)
But you're being too dismissive of how people displaced by gentrification feel. It feels rather arbitrary (It's not like the free market is pricing them out because someone else can pay more because they can make more optimal use of that particular land), and while they are not "the poor bastards in Somalia", you're still on one end of the spectrum and they are a little closer to the Somalis.
On the other hand, if it's privilege bratty hipsters that are complaining about being pushed out of the Mission, I'm totally with you.
I live in New York now, and it's extremely obvious that gentrification isn't some color and privilege-blind blossoming of wealth that expands outward engulfing everyone in its path with prosperity. There's little engulfing. It's more of a bubble with high surface tension pushing out. The inside of the bubble is white, and the outside is black.
The crux of the issue is that it resulted in a less healthy/hungry city because it made it that much harder for someone to come to SF, find a place to rent, and then work at whatever startup idea they wanted.
In the long run, its just a sign that a particular city/era's time has come/gone, and should be lauded.
The opportunity to start a new network elsewhere and build a fresh system to improve on the old is what I can see here.
The parts of the city that aren't fashionable haven't seen a meteoric rise in prices: people aren't being pushed out of SF, they are being pushed out of hipster SF.
...how? From what I can tell, here in SF, "subsidized" housing is requirement for folks who are building new apartments to "Set aside a certain number of apartments for people making 90%->120% the area median household wage." and/or "Subject a certain number of apartments to the city rent control ordinances.".
If you're living in a rent-controlled apartment, it's not permitted for the total amount of rent that you collect from all of your roommates to be more than the amount of rent you pay your landlord.  I don't know the details of how the "low income" housing program works, but I would be floored if there weren't periodic checks to ensure continued income eligibility and to ensure that folks aren't making a profit off of subletting.
 If you're profiting from your roommates, your roommates can go to the city Rent Board, who will then require that you return the excess money back to them.