Selective incorporation as it implies with the question you asked.
In short, excessive speculation.
During the 1920s, the United States economy saw a period of massive growth and everybody wanted in. So, many people overleveraged themselves and got into financial speculation. People did well for a while but the music eventually stopped as the market hit limits and the house of cards came tumbling down as many people didn't have the money to back their bets.
Answer:
The Japanese navy and air force were destroyed. The Allied naval blockade of Japan and intensive bombing of Japanese cities had left the country and its economy devastated.
