People tend to go to jail for malice (willful intent), not mistakes. The financial crisis was viewed as just a giant mistake in risk management. having a 20-sigma event when your financial model says it is an impossibility, is not a crime.
Conveniently, money is extracted along the way in the form of generous fees, everyone apologizes for the thousand-year event they couldnt predict, and we repeat the cycle. People on the outside make excuses while those on the inside craft brilliant tales of hard work and rugged individualism.