First off, I haven't read all friggin17 pages of discussion, so i apologize before i may say something someone else may have tossed into the mix.
The USA, is by far one of the most economically vital countries in the world. If the US fails, well, there would be very much fallout worldwide. It would be a huge blow to the world financial market, much as we saw back in 2008 during the beginning of the current recession.
There is what is known as market wave theory, and I am sure some of those out there familiar with financing and accounting have heard... I am a biophysicist... I have a BSN-Emergency Trauma (military degree), and also found the time (and not much life for another 3 years) to pursue a Bach. in BME, and am working on a master's in biophysics, and one of my professors runs a financial firm that is doing well... basically, the market, overall, is on a steady, VERY SLIGHTLY growing trend. Regulation only steadies such growth, however takes most opportunity out, thus less people are able to start businesses, let alone just be highly successful. Deregulation takes us into a rapid wave pattern of ups and downs. Now on the upswing, more people have a chance to become more successful, thus the spikes up always outweigh the bottom of said waves. Markets that are allowed to experience some waves, last longer, and stay stronger, than those which are attempted to be wrangled onto a constant flat line. This is why tachyons are theorized to move faster than light... their rapid wave patterns, which happen to be the only evidence of their existence... can move between all energy and all matter, without interruption of space or time.... now, sure, you don't want the spikes in the wave to wrangle way out of control to the extremes, but at the same time trying to regulate and control it is only like making a bridge too rigid... that rigidity only becomes the very cause of it's demise....
If the US is starting to fail, more than financially, it would be disaster for the world. First off, the UN, and really any other country can forget about trying to step in to 'help'... because here in the USA, we take care of our own problems, not go around to other countries looking for handouts (talking the country in whole... the people... not the govt, as it would have failed in this case...) and we definitely won't take kindly to people forcing their way in. You may think the situations in Iraq and Afghanistan are uber shitty and fucked up (they are in many ways.. spent over 4 years between the two...) however, you have not seen shit, till someone stirs up this hornets nest. 1/20 people own a firearm in the US, with most owning more than one. We are the best armed country in the world. So this leaves out the possibility of any other country 'taking over'.
Now I personally would welcome economic collapse followed by civil collapse... because only then can we take out the trash that has held us back/down.... for then, we can finally regain our freedom, and our country, and restore it to it's former glory and respect.... and make the USA once again, the country everyone at one time looked up to.
Oh and by trash, I am talking all the corruption, and criminals running our country at all levels... but hey, that is just my opinion... seeing how Marijuana was made illegal at the request of old pharmaceutical companies under the later laws (1960s and later) and originally by some of the original monopolies.... so it is only very relevant... Unfortunately, the USA is not alone in this plight with govt corruption... it exists anywhere that an individual is given any power or authority....
