I do not plan on living with my parents forever. Basically I can either pay like $1000++ per month to rent, which would be money I never see again, or if you have saved up money like I have, I can get a loan and buy something and spend about the same paying down the mortage. Money well spent, because at some point (like 25-30 years) I will own the apartment outright. Of course I will probably not remain in that apartment for the next 25 years, but it is basically an investment. There are only so many places to live in central Oslo, and the demand is always going up. And even if the market crashes and I lose a lot of money, the prices of all the other apartments will be lower as well, so I would be able to buy another place at an equally lower price.
Loan interest is very low at the moment, around 2.7-2.9%, and to counter everyone loaning way too much, you need to have 15% of the loan sum in order to qualify. I can expect to pay maybe $320k for a apartment in Oslo, depending on how big and where it is. $320k would typically be >50m2 somewhat central, or 30-40m2 very central (those go for even more).
I will need to have about $48k in cash to be able to get a loan at that price.
I also have some student loans, but I have basically my whole life left to pay them off at a very low interest, so I pay like $154 every two months or something I think. It is the best interest loan I am ever going to get, so there is no point just paying it down immediately even if I have the cash for it.
TL;DR: Paying for a mortage is better than paying someone else rent, and I do not want to live in my parents basement forever.