This is because the overtly stated goals and the actual incentives are not aligned at all, they're closer to diametrically opposed. The stated goal is "build m

This is because the overtly stated goals and the actual incentives are not aligned at all, they're closer to diametrically opposed. The stated goal is "build more housing so everyone can have a place to live", but the current incentives are "bundle these materials and labour under guise of another product so you can sell it for a profit". Of course developers walk away when prices drop -- their objective is to make money, not housing. The fact that they build homes people live in is purely incidental.