There are several reasons housing is expensive. Not creating alternatives to 100m2 750.000€ houses is one of them.
I'm thinking let people do work from home, buy a ceap plot outside of cities and put a camper on or tinyhouse or even stacked containers which work great for refugee homes. We were living in caves for the longest time of human history. Then they can save the rent to eventually build an actual house if they want to.
I know people living in 2 constructionwagons like Peter Lustig. If by choice i prefer this over seeing elderly having to collect deposit bottles.