Is a house actually necessary? I've been content with living in a rented flat so far. Or is that mainly an American thing where outside of larger cities space is abundant?
Depends on your situation and how long you plan on living in one place. In the US there are tax advantages to home ownership, my mortgage + property taxes are currently less than what I would pay for rent for a comparable house. Situations differ by individual and region. Some places like San Francisco are seeing rents go through the roof, while some places like Berlin are still very reasonable.