>Because as the population grows, we need an equivalent amount of new housing.
In the UK (but also most elsewhere), population no longer grows. If censuses say differently, it's because immigrants are being imported from overseas, not from any organic growth. To believe that this is righteous is a strange thing, one has to accept that British people should suffer so that immigrants can gain.
Because as the population grows, we need an equivalent amount of new housing. Short of that, we compete for limited inventory and prices rise.