What you're referencing is not a law it's a referendum that most likely will never be adopted as it's illegal. On top of that, how does that referendum affect your friends unless they run a giant business with thousands of apartments (to be exact 3000 or more)? And at that scale it's certainly cheaper to fight in court.

> is not a law it's a referendum that most likely will never be adopted as it's illegal

It reflects a political environment that makes renting risky. And illegal laws can still cause hardship while they're being stayed and struck down. The corporate landlords can afford to fight. Single-home landlords cannot. This time the referendum constrained itself to corporate landlords; next time it may not.

From the outside, this sounds scary. But if you look closer how germany works, forced selling to the state or city (at the current market price) is quite often happening in building infrastructure like streets, autobahn, railways or airports. If there is an overwhelming public interest, the rights of owners can be limited.

And btw: it's stated in the constitution, that ownership introduces also responsibility to the society.

> If there is an overwhelming public interest, the rights of owners can be limited

Eminent domain exists everywhere. Berlin’s politics are more extreme than the norm. Most homeowners would pay a low single-digit percent of their home value to insure against expropriation in that environment. Taking a property off the rental market is analogous; sacrificing a cash flow to safeguard the investment.

We can go back and forth on theory all day. I’m m reflecting what people I know are doing. Being flippant with (or even demonising) owners’ interests circles back into affordability crises worldwide, from Berlin to San Francisco.

Same in San Francisco. My old landlord never rented out my old place when I left (3 unit building). She was getting close to retirement and had gotten advice that the building would fetch 2-3x if fully unoccupied. So she was just waiting since giving up $40,000/yr in rent for a $500,000 higher pay off is an easy trade off.

People forget that you can always “price in” regulatory changes. Then you just see which path maximizes profit. What may seem ridiculous (leaving a unit empty) actually makes a lot of sense based on the rules.