As a longtime advertising/marketing professional, Martin, I can assure you that marketing research is often really shoddy work--more often than not, it is contrived to support the view of who ever happens to be calling the shots in the corporate boardroom--

The real reason that these guys are expanding is that their business model requires expansion and they have the capital to expand--when the capital disappears, they sell out, close down, and move out--it costs more to stock and operate these mega-stores than it does to build them, once they go into the red, they have no hesitation about shutting them down.