The 1920s was a time of enthusiasm following World War I. They had the
sense that anything was possible with new inventions coming out, like the radio and
airplane. Although the stock market has always posed a risk, the
optimism of the people in the 1920s was too great; they ignored it. They
pulled money from everywhere, investing their entire life savings.
Because the governments of the world printed a lot of money during WW1 to pay for the war, the inflation didn't catch up until the 30's, which made the "roaring twenties" possible.