They are, as the article explains, real-estate investors who do not always examine properties before purchasing them. The couple knew that Presidio Terrace was in a nice neighborhood and seemed to be very well-priced, and they also were bidding in many auctions, so that they probably would not have cared about precisely which properties they acquired.
There is always risk in investment and investing in property sight-unseen is perhaps very risky, but they felt like it was worth it to them. As the article said, sometimes you can sell off their investment for a profit. Other times, evidently, you can annoy the politically powerful.