The desire to own high-end goods is not exclusive to the rich and well-off - in a recent survey among Millennials, for example, the general tenor indicated that the majority of them like to treat themselves to luxury items on certain occasions. The global luxury goods industry is thriving, and the United States is at the forefront by far.
Disposable income in the United States has increased over the last decade (though, to be fair, so has the cost of living), and there is a trend indicating that Americans are often willing to pay more for (if only perceived) higher quality and additional benefits, be it for housing, travel amenities, or clean energy, for example.
Affluent Americans are a highly sought-after consumer group, and not just the millionaires; interestingly enough, most millionaires do not consider themselves upper-class but rather middle-class, so retailers often advertise luxury goods as goods of higher quality, tradition, or exclusivity, accessible to everyone with the right amount of money - i.e. affluents in general. Quality and brand name recognition are the most important factors when it comes to luxury items, after all.
With the right kind of money at their fingertips, affluents are most likely to spend it on fashion items, cosmetic procedures and treatments, or experiences and hobbies like travelling or boating. Luxury cars are not that popular anymore, but hybrids are. All in all, affluents today are more interested in spending their money on experiences rather than on goods, and big box retailers are definitely not off the table.