People weren't buying stocks because the companies were profitable; they were buying because they expected the price to go up tomorrow. This is the definition of a speculative bubble. As long as prices climbed, the system held. But margin buying has a "trap door" called the The Trap Door: The Margin Call
The 1920s, often called the "Roaring Twenties," was a decade defined by jazz, rapid industrialization, and an almost religious faith in the American stock market. For the first time in history, the average citizen felt the lure of Wall Street. However, this era of unprecedented prosperity was built on a fragile foundation: buying on margin great depression
By 1929, an estimated was out on loan to stock speculators—more than the total amount of currency circulating in the United States at the time. This massive influx of borrowed money disconnected stock prices from the actual value of the companies. People weren't buying stocks because the companies were