Well, there's always that, but I've always figured it's about taxes and government spending. There's a very large amount of over-valued houses in and around the larger cities in Denmark. If the property value goes down, so does the property taxes, which means less income for the local authorities.

There are cheap houses available outside those areas, but getting a loan for them can be tricky since their value is too low and there's no money to be had from lending the money.

Furthermore, most people have their homes as security (not sure if it's the right word in English) for their loans. If the property value drops then many will be forced out of their homes. Also a lot of landlords and real-estate agents, will be out of a job, but that's probably a smaller issue.