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.
For the specific example of buying apartments in Oslo to rent out, sensible analysis will show that this gives a worse risk-adjusted return than other options (e.g. the stock market). But hey, go right ahead. It's not my money ;)
If you believe in long term economic stability, then go ahead and invest in stocks. We don't. And now we know at least we'll have a place to live.
When economy is stable, realty prices grow; when economy is shaky, realty prices fall but slower than stocks. Stocks are more liquid on the other hand.