What caused the 2007-2008 financial crisis?

Context: The preconditioning for the financial crisis were complex and multi-causal. Almost two decades prior, the U.S. Congress had passed legislation encouraging financing for affordable housing. However, in 1999, parts of the Glass-Steagall legislation, which had been adopted in 1933, were repealed, permitting financial institutions to commingle their commercial and proprietary trading operations. Arguably the largest contributor to the conditions necessary for financial collapse was the rapid development in predatory financial products which targeted low-income, low-information homebuyers who largely belonged to racial minorities. This market development went unattended by regulators and thus caught the U.S. government by surprise.

Answer: Arguably the largest contributor to the conditions necessary for the financial collapse was the rapid development of predatory financial products which targeted low-income, low-information homebuyers who largely belonged to racial minorities.