"A desire to learn" and "Make new contributions to human knowledge" are laudable goals that I admire. But, even leaving aside the important question of whether grad school as it is currently structured is a good way of pursuing either, it's hard to make new contributions to human knowledge when you're having trouble making enough money to support yourself, and it's frustrating to see your new contribution made when your buddy is working for Google and writing software that millions of people use every day—and getting paid well for it.
It seems not unreasonable to me to balance life / career goals with learning and wealth. The opportunity costs of grad school are incredibly steep. If you are the rare person who doesn't care at all about material possessions or the physical quality of life, then by all means go to grad school. But if you go expecting a tenure-track job at the end—which most people seem to—then you're making a mistake. I am not at all opposed to someone who simply says, "I don't care at all about income."
Also, I'm not sure you're calibrated correctly. It's not about sacrificing "latest model cars", more about sacrificing a reasonable chance of retirement.
I have too (see here: http://jseliger.wordpress.com/2012/05/22/what-you-should-kno... for some comments, mostly job-related), and I think most grad students—at least during the first half of their experience—do think they'll be the exception.
They are rather intelligent, motivated individuals, who choose to work on projects that are more interesting/important than optimal ad placement or crafty financial swaps, and who are prepared to sacrifice some Caribbean cruises and latest model cars in return.
I think we'll have to agree to disagree. Most seem to be pointlessly delaying adulthood. Note that there are exceptions.
Without data the rest of this discussion might be pointless, but the prevalence of articles warning against PhDs seems to me to point in an important direction.
However, it is true that a disproportionate amount of jobs will follow the money.
I don't think the average grad-student could work at Google instead. My personal experience is that Google keeps having its recruiters call me periodically, and then rejecting me for even internships after interviewing.
I don't even get the questions wrong anymore, so I feel like I just somehow suck, despite being a CS grad-student at a well-regarded institution.