Or worse like where I live (Switzerland), people rent flats, then subrent them for a lot more and go live in Thailand (or somewhere else). And then we all complain because the prices for (renting or buying) flats is insane here.
The real problem in your situation is that these people are able to rent flats for sub-market prices. But it's not your problem. Your problem is that you don't have enough realty supply. And/or more people who want to live in interesting city than interesting cities of Switzerland can house.
The latter seems to become a major problem in most countries.
(b) Switzerland is crazy expensive. So you can probably make megabucks renting out property there.