There should be absolutely no dispute here. It was Wallstreet GREED. People were allowed to buy on margin (money they did not actually have)...anticipating a stock price to increase. Stock prices hit a critical mass point, then collapsed. Without gov't intervention into the credit market, business failed all over the country - the domino effect
The Wallstreet boys did it again starting in the mid 90s and up to 2007, then COLLAPSE. This time, however, there was a gov't bailout.