I once read a fictional story about a 20 year old selling his remaining lifespan except 3 months for 30 yen. Imagine how awful that life must be if it only sells for 30 yen. He didn't know it when he sold his lifespan, but his future self would have spent his remaining life in a hospital after an accident. The moral of the story is that it turned out to be a good deal.

Those flats are the same. The $15,000 is probably an absolutely fantastic deal for the seller. There is a reason why the apartment is so cheap. You get what you pay for and it's most likely crap.