Final answer:
The historical events in the 1970s that caused the film industry to become disillusioned with the 'American Dream' include the Vietnam War, Watergate scandal, and economic stagnation.
Step-by-step explanation:
In the 1970s, several historical events led to the film industry becoming disillusioned with the 'American Dream.' One key event was the Vietnam War, which highlighted the flaws and contradictions of American society. The Watergate scandal also shook public trust in the government, and economic stagnation caused by factors like the oil crisis further contributed to a pessimistic view of the American Dream. These events challenged the idea of progress and idealism, which the film industry had often depicted in its movies.