That $5 trillion dollars is not money invested in building roads, schools, and other long-term projects, but is directly transferred from the American economy to the personal accounts of bank executives and employees.
What does the author believe the bank executives and employees do with that money? Some of it is spent on consumption, but most bank executives consume a far smaller portion of their income than anyone else. [1]
Whatever they don't consume is reinvested in the economy.
[1] If you disagree with this claim, then it logically follows that the best form of Keynesian stimulus is tax cuts for bank executives.