What triggered the financial crisis? Why is there a financial crisis? thank you

The direct cause of the world financial crisis is the American subprime mortgage crisis, mainly the American subprime mortgage. Now the United States has triggered a series of influences, which led to the bankruptcy of Lehman Brothers and then expanded to the whole world! The financial crisis is mainly caused by various financial derivatives in the United States, because the manufacturing industry in the United States is gone except the arms industry, Boeing aircraft and the three major automobiles, so the American economy mainly relies on the tertiary industry and high-tech industries, especially the financial industry. American financial innovation is very strong, so there are financial derivatives. Undeniably, these financial derivatives have indeed promoted American consumption, thus promoting economic growth, but they have also planted a time bomb for the future! US Treasury Secretary Timothy Henry Merritt Paulson fully supports financial derivatives. During his tenure, financial derivatives have been greatly developed, but Warren Buffett and alan greenspan both oppose this policy, thinking it is a time bomb for the economy, especially Buffett, who has never bought any subprime bonds! ! There was a crisis, and everyone was watching in America. First Europe satirized America, and soon it was Europe's turn. At first, he laughed at the United States, but a month later it affected our country. I will graduate next year, and I feel a lot about finding a job this year. The starting salary is low this year, and there are many fewer companies coming to our school to hold job fairs than in previous years! ! Many companies have temporarily cancelled their recruitment plans or reduced the number of recruits! For example, Foxconn recruits many people from our school every year, and none of them came this year. I heard that Foxconn laid off 80,000 people worldwide this year! Our country has also begun to take measures to stimulate the economy, not only reducing the application conditions for loans, but also investing 4 trillion yuan in infrastructure construction to stimulate domestic demand and promote economic growth! ! Sorry for making so many complaints, please forgive me (* _ _ *) hee hee. ...