It doesn't matter if an item is "high end" or not. If you can't eat it, wear it or sleep inside of it, it's a luxury. We're all guilty of spending more than we have to on our hobby....because bottom line is it's just a hobby and we can easily survive without spending a penny on it.
Most of my friends are perfectly happy borrowing their DVD's from Netflix, playing them on their $20 Sungale DVD players, watching them on their 27" Emerson televisions, and listening to them through the television's speaker....perhaps not strangely, every one of them drives a newer car than I do. Even with a system this modest, they're spending more than they need to.
It's been my experience that the wealthy are just as likely to comparison shop as the not so wealthy. Some have a Krell vs. Classe budget and some have a Denon vs. Onkyo budget. Comparing specs, reading reviews, auditioning equipment and working towards the best value is part of this hobby. "What can I do to best improve my system, that’s within my budget?" The exception is that there are the folks who just don't care about AV as a hobby...only the end result. Those are the folks who, if they have the funds, write a check to an installer and leave the details to him. They also aren't upgrading/swapping parts/tinkering regularly. They don't tend to hang out in the AV forums. They really aren't that interested.
In the end your "high end" superfluous items flood the marketplace because there are consumers for them (if not, they don't last long on the market). Whether it's marketing hype or a legitimate rationale, there are consumers for these items because people perceive a value to them....and have the buying power to obtain them.
We live in a consumer oriented society. We have income in excess of what we need to survive. So, we have money to spend on things we want, as well as things we need. People with more money, and more importantly people who perceive quality and performance to be of the utmost importance, are willing to spend more. A very few (thanks to the ease of obtaining credit) will buy more than they can afford. Most won't jeopardize their necessities...food, clothing and shelter. I don't think in most cases there are any sinister psychological handicaps causing people to spend more. In the end, it's simply the availability of funds and a perceived value to quality.