If you were wealthy why not put in the tiny bit of extra effort build a well constructed, nice, huge house that will last for generations?
In many (not all, not most) cases, the builders locate the house in an area completely unsuited for the property. They'll find some low-cost home in an established neighborhood of 30-40 year-old ranch homes (for instance), then tear that house down (or maybe they'll buy two lots next to each other!), then build the monstrosity that towers over everything else in the neighborhood. They'll get variances and whatnot to build nearly up to every property line within fire-codes.
It becomes a nightmare for the rest of the property owners; usually their homes will decrease in value as a result, due to nobody wanting to purchase or live in their home with such a structure nearby. Of course, this may cause them to sell their property at a loss - perhaps to another developer who puts up another such McMansion...
There's such a thing, when you are building in an established neighborhood, to be a good neighbor and build something that fits in (both style and size) with the rest of the homes. Same if you modify the existing home; you don't want to go too crazy with style or structure, because this can devalue properties around you. It all comes down to whether you have any empathy for other people; whether you can place yourself in their shoes and say to yourself "if someone were doing this to a house near me, would it be a problem?"
Unfortunately, too many people that do this don't care, or can't empathise - or if they can, again - they don't care. They just want to build, and flip it for the cash. It's a grab, plain and simple. Rarely do the people who build these live in them, because that would put them at the ire of their (now ticked off) neighbors.
Externalities are, as it happens, not your problem.
This is proving to be more of a bug than a feature, huh?
Suburbia seems to grow evermore malignant with each passing decade, and so many assholes are couched in lives of ostentatious comfort without ever having to think deeply about what that means.
There's something about driving an hour to work, being bitched out by middle-management all day, driving an hour home, and having nothing but strip malls, video games, tv and the internet to show for it. A fraction of these people have romantic relationships with a significant other (as parsimonous and avaricious as they), and the rest suffer a solitary existence, but maybe with a circle of familial relations that don't actually help matters.
With that, empathy becomes effaced in the slow acid bath of an eight hour (or longer) work day, and then incinerated by the blow torch of a lifetime wasted on spare time in a place where nothing else can be afforded beyond transportation, processed food, and a boondoggle or two to keep you sane enough that you don't snap and kill any of your peers.
Every now and then one miserable suburbanite proves useful enough to be rewarded with a looser collar and a longer leash. This is where the unapologetic, leering McMansion enters the picture.
Math checks out to me.
(Oh, and she's not a "girl", she's in her twenties, unless we're going to play the "use the term 'girl' to minimize a woman" game and we're not, and that 99% Invisible episode strikes me as pretty good because it reveals what people don't think about, as is their stated goal.)
I know someone who sends letters repeatedly to GEICO because he hates their commercials. Why waste the effort?
They are literally building semi-permanent garbage on the face of our only inhabitable planet.