Why housing costs are high in European cities

‌1. Naturally, people tend to flock to metropolitan areas.
2. Since most buildings in large cities are cultural heritage sites, redevelopment is difficult, making it hard to increase residential space.
3. On top of that, most refugees and immigrants settle in major cities.
4. Tourists flock in and fill up Airbnbs, further reducing the residential space available for citizens.
That is the general consensus.
Excessively high housing costs are also cited as one of the causes of the recent protests...