Just in case you're in a position to change anything about the housing market where you live: Change zoning rules. Incentives for co-living. Reduce flat sizes.

Just in case you're in a position to change anything about the housing market where you live: Change zoning rules. Incentives for co-living. Reduce flat sizes. Rebuilt office spaces. Or look to Vienna: a big stock of goverment-owned flats with low prices which makes it hard to charge more than those.