It is of course not common to rent for 30k because most people feel they can't afford that but it is essentially the "spot price".

Many apartments in central Stockholm are ~100k SEK per square meter to buy. So a 100 square meter apartment is 10 million. That is 16-17k per month just to beat the inflation target. Then you have the building fee which is probably 4-5k. And then profit on top of that of 8k per percent. So with 1% profit you are more or less at 30k per month.