When you can't add more housing, rents have to rise to push people out
You won't catch me saying that any new housing is a bad thing. I get that supply and demand works from top to bottom.
But the question is, if we took an Olympian view, of the total money being spent by society to create roofs over heads, which projects put the most heads out of the rain, per dollar?
As long as no public money goes to housing the rich, permitting them to house themselves as finely as they please must be an option in a free society. But I have no problem taxing construction so heavily that a $4M house really has to give up one bathroom, and a parquet floor, to come in at $3.8M, because society snitched $200K to house a whole other family.
Progressive governments don't "hate" the wealthy any more than hotels "hate" people who stay in their best rooms. The high hotel rates are just what you pay for the best room.
At least there's no question any more than governments are on-side. It's about the NIMBYs and the government's understandable fear of them. As Roosevelt said about the New Deal, 'You have to get out there and make me' - governments need visible public support, shouting (and voting, and contributing) down the NIMBYs as they rise.
The opposite of gentrification is 'filtering'. I've wracked my head over and over again to try to come up with a way of explaining to people that if you build enough housing for the well off, there's a supply of old, not-well maintained housing that becomes cheaper to live in. If you don't, the old stuff get's eaten up by gentrification.
But that idea simply doesn't get any traction. A friend who used to be mayor of my city just dismissed the idea as "trickle-down" housing. I see on FaceBook a meme that shows an empty shelf and a cartoon figure who says that that's where all the studies that show how housing for the well off helps the poor find places to live. I recently did a quick Qwant search after seeing someone repeat this nonsense and found a half-dozen academic papers on the subject. (Unfortunately, Meta wouldn't let me post them---I suppose an old economics thesis is now 'news' according to their algorithm.)
There's a real problem with 'progressive' people's hatred of the wealthy distorting their way of looking at housing.