In a way yes. But its also using leverage to amplify your gains.

Say I get $90,000 to go buy a house, I spend the $90,000 and have 1 door. I get a tenant in it and they make a $90,000 down payment. I then go buy another house and get another tenant in it and they make a $90,000 down payment. I now have two houses and still have the same amount of money I started with, I can continue this cycle and as long as property appreciates I don't just get the property appreciation from one house I get it from all of the houses so (% appreciation * property value * number of properties).

Say it is a $100,000 property and it appreciates 3%. If I had just bought one house and put the money in an interest yielding savings account I would get some low % return. If I instead chained it to acquire 10 houses I would get $30,000 return, which is 30%. But if the value of the house goes down it works against me!

Obviously this ignores transaction costs, interest costs etc.

> Say I get $90,000 to go buy a house, I spend the $90,000 and have 1 door. I get a tenant in it and they make a $90,000 down payment.

Why wouldn't the tenant spend $90,000 on the house themselves, cutting out the middleman?

Korea has a housing lottery where they give you first dibs on a new apartment at an extremely discounted price with financial assistance. Due to demand, this housing is difficult to get even at full price. However this lottery is only available to first-time homeowners. So my friend chose to do cheonsae instead of outright buying a place to save his housing lottery ticket.

Usually cheonsae deposit is less than 100% of the purchase price, so it costs less. Even if the difference is small (10%), you are guarded from drops in real estate value. If you put down $90,000 deposit you should get back exactly $90,000 even if the property value dropped below that.

And perhaps cheonsae loans are easier to get than house mortgages. I'm not sure about this, but the deposit may be better collateral than the property?

This feels like it should be illegal. Just by random chance there will be a point in time where enough tenants ask their deposit back at the same time, and you enter one big economic crisis. Of course, banks also have this risk of a bank run, but the difference is that big banks are tightly regulated and have a strict reserve rate they have to abide to (usually >5%). I wouldn't trust a big population of landlords who manage their own finances, and have a big incentive to cut corners.

If anyone knows a method to short Korean housing, please let me know!

What happens if two or more tenants want to move out at the same time? With the strategy you describe the landlord only has cash for one reimbursement.

Sell both properties and realise (perhaps pre-maturely) the capital gains?