There are several factors that made the Wall Street crash inevitable. There was an overproduction in American industry, the wealth was not evenly distributed, there was a restricted market for US goods in other countries, speculators "played" the market with borrowed money and there was an enormous panic to sell shares in October 1929. .
New methods of mass-production and mechanisation meant that production of consumer goods had expanded significantly. There was an over production-more was being made then could be consumed and the market couldn't handle it. The people who could afford the goods had bought what they wanted but too many goods were reaching the market and there weren't enough people who could afford to buy them. .
The wealth of the 1920's wasn't evenly distributed among the American population. Almost half of the American families had an income of less then $2000 a year that was a level of income that only bought the bare necessities of life. Farmers and farm workers were just barley scraping a living and new immigrants were given the lowest paid jobs. The African Americans were constantly discriminated against. The majority lived in poverty, both in the rural south and northern cities. Workers still in the old industries were paid very low. The smashing of the trade unions meant that workers had little power to bargain for better wages. .
US goods had a restricted market in other countries. Its was unable to sell its surplus products to other countries especially Europe despite it being a big market. The European countries couldn't afford American goods because they owed the USA reparations due to the war and were struggling to pay them back. The US government had also put high tariffs on imported goods and American businesses were too strong to let European companies sell their products to America to earn enough money to buy American goods. .
American businesses were so successful that they made the market do extremely well.