It's fallaious to not consider the market value of your assets as well as any income streams. In fact, this example is even worse because it also doesn't consider the cost of capital and fluctiations in the income.
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 ;)
Stock market is prone to crashes; also you can't live in your stocks when out of other options.
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.
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 ;)