The American Dream was created in a time before people (at least some intelligent, thoughtful, non ignorant-blob-consumer-robot people) realized that infinite growth theory does not play out so nicely within a finite resource reality.
Unless I am completely off base, the American Dream first became a generally agreed upon idea when the people in power played on peoples' dreams of having a meaningful, fulfilling life while improving ones station, or at least that of their children, telling them they could achieve all of their wishes by being independently sustaining, home owning, honest laboring, and family making citizens, all in order to subtly fulfill the oddly megalomaniacal theory of Manifest Destiny.
Manifest Destiny was originally the theory that it was America's destiny to spread across the entire continent, and when we got as far as we could with that, it sort of shifted into spreading American ideals, namely capitalism and freedom (aka American Democracy), across the globe.
This in turn shifted to what we know America's role to be today, which is the elite world police force, hiding in the shadows of the United Nations and NATO, (which we always seem to spearhead, weird right?).
Based on several admittedly outspoken independent films and even a few legitimate documentaries, I have come to believe this apparent need to always be stretching our authority, interfering and to have a LOOOOONGGGGGG military arm always fishing around in the global cookie jar has simply become 1. An excuse to maintain a disgustingly large military-industrial complex which produces a huge number of machines whose sole purpose is to piss metal and fire on the unfortunate souls who attempt to resist our whims, so to keep our GDP and all those other meaningless numbers and ratios and whatnot on the up and up (and pad the pockets of the defense firms who contribute immense sums to fund campaigns for politicians who invent the wars. 2. An excuse to continue finding and maintaining fake "wars" (by the way, does anyone know the last time congress actually declared, (or ratified a presidents decision to go to), war? WW2. Go figure. I'll go into the bullshit surrounding the imperial presidency later.) so they have reasons to take more money from our paychecks and slowly chip away at our constitutionally granted freedoms, which appear rational when claimed to be a result of "maintaining national security". (Edit: I would go into how I believe that this slow and steady loss of personal rights and privacy is just a calculated process of acclimation to a NWO, within which we literally have no agency to fight back because by the time the majority realizes that what seemed like a rational progression of legislation passed for our "security" was actually the removal and abolition of such popular rights as Freedom of Expression (long fucking gone, what with conventional mass media in the pocket of lobbyists and interest groups), the Right to Bear Arms, (or arm bears, which I have found is a sometimes equally if not more effective defense strategy), or habeous corpus, and the list goes on.
I apologize for that lengthy tangent on Manifest Destiny, but it is critical to understand that if you want to understand the progression of the generally accepted American Dream. I think everyone can agree that, while one might be able to google "the American Dream" and find a few similar, generally accepted definitions for the term, that most Americans' dream, or perhaps more accurately, their desperate hopes, have long since changed, and become quite more humble.
I think it is safe to say that the horrifyingly large percentage of American's who are homeless, or living below the poverty line, or who are trying to survive on unemployment, or perhaps scariest for me, the shocking number of young adults, who relative to the majority of the global population are highly educated and/or skilled, who can't find ANY job, or have to settle for a menial, piss-poor job to slowly make the minimum deposits on their $100,000+ student loans, which, for anyone who understands compound interest and market shift trends, knows that the total is much higher, that their American Dream has become a desperate hope to hold on, survive, and maintain their current class, or at least not drop too much lower, until things improve. And because of the sense of apathy that has become commonplace in this country, they do not have the motivation to CAUSE that change themselves, and simply complain about the faults of corrupt government and poor economic forecasting.
Even those who are living relatively stable lives, who have dodged layoffs or technological unemployment or outsourcing are still battling rising prices, credit interest rates, which they didn't know to factor into their ten-year plan which was originally attempting to pay off a mortgage, afford christmas, and save up enough to send their kids to college and then live on the dog food social security can buy when they retire.
TL/DR The oldschool American Dream was a subtle nudge to get people to fulfill the elite's goal of Manifest Destiny, and as Manifest Destiny changed over time, it has effected the reality of living in the US, and thus the outlook, hopes and dreams of U.S. citizens.
