I also get annoyed with the requirement of 'solidarity' in pumping housing prices up. However, in case you want to understand one motivation of the mentality,

I also get annoyed with the requirement of 'solidarity' in pumping housing prices up. However, in case you want to understand one motivation of the mentality, consider that people not only roll equity into another house. Many (questionably) use their homes increased value as collateral to borrow money to prop up their lifestyle. Those who leverage their home equity this way can be in deep trouble if housing values go down in a significant way. The bank could call the loan (forcing early repayment, or sale of the home if they cannot).