While their may once have been a time when Wall Street could have been considered the engine of American finance, it has become in actual practice little but a high-fashion casino. (Perhaps Bernie Madoff made it too explicit, but in reality his Ponzi scheme functioned for so long, and with so little investigation, precisely because it did operate much as any of the other high-roller operations that it mimicked.) Credit default swaps (at least, as they were implemented) served exactly one purpose, which was to give uninvolved parties a roundabout way to bet large amounts of money on something that was, due to the inherently untangleable mess of the underlying "assets", of unknowable value. Like much of the financial inventions of the last decade or two, it did nothing to stimulate any part of the economy other than finance itself. It created no jobs, except the jobs required to push paperwork from one desk to another. It created no new products, and invented no new technologies, and it gave no money to any party interested in doing either. And America boomed because of it.
That is the nature of the new kind of "finance" that continued to represent a larger and larger share of America's ostensible "prosperity". We have become a nation incapable of effectively making textiles, cars, steel, electronics or other physical things, because those things only allow for a little profit. Instead, we choose to dabble in the strictly theoretical profits of high finance -- imaginary profits on imaginary wealth. Finance became more and more speculatory, and less and less encumbered by physical products, or assets, or services.
And the rich have done exceedingly well for themselves, in that new economy. As for the rest of the nation, the middle class found themselves subjectively in a recession for the entirety of the Bush years. Food prices, gas prices, housing prices -- on every front, it became harder and harder for the middle and poorer classes simply maintain the status quo, and yet none of this counted as recession or poverty, because we simply kept redefining the terms to exclude such unpleasantness.
What did we gain? Ask yourself -- what, exactly, did the nation create during those years? What new projects did America embark on? What betterments did we make to the lives, or health, or happiness of our citizens? What did we do?
The answer is jack-squat