The trick is that you can get a loan to pay the jeonse deposit. The interest rate for jeonse loans is considerably lower than for a regular mortgage, and until recently even lower than paying rent, because these loans are effectively guaranteed by the landlord who is contractually obligated to return the money.

So if you simply wanted to live in a certain area for a while and not get tied down by the legal burden of ownership, getting a jeonse loan would have been a steal compared to a regular mortgage or even renting.

My first jeonse deposit was $90K, $60K of which I borrowed from a bank. Interest on that loan was less than $150/mo. Rent on a comparable apartment would have been upwards of $500/mo at the time. Of course you can't get this kind of deal nowadays, but the scheme made a lot of sense when it worked.