The Federal Reserve System catalyzed the growth by reducing interest rates. The growth was false, built on artificial premises and poor management of banking and markets
The market had to keep growing in order to prevent collapse, and in doing so it became more dangerous for when it would collapse. There were very small dips in the market, enough to make a difference but not enough to stem the flow of overzealous investing.
Politics made their way into the market, as political bigwigs made deals and connections with business owners and influenced the market through policy.
The election of 1928 also impacted the stock market and prices continued to climb as speculators kept predicting rising prices in the market with the changing political climate.
The Federal Reserve Board, even though they raised interest rates, found that in order for the market bubble to stabilize, it must first crash and would affect everyone who has money invested.
The Federal Reserve set high standards on loaning money, in an effort to control the climbing growth.
After a brief crash, bankers and other organizations artificially propped up the market through loans and tried to keep the the growth going. With the growth of the market, business changes tactics to tailor to the market. New investment firms sprung up like bad weeds to cater to the growing demand of the public.