Any informed borrower is simply less vulnerable to fraud and abuse.
Amateurs want to be right. Professionals want to make money.
Greenspan, who knew so much more than most, knew far less than most supposed.
History has not dealt kindly with the aftermath of protracted periods of low risk premiums.
What we have found over the years in the marketplace is that derivatives have been an extraordinarily useful vehicle to transfer risk from those who shouldn't be taking it to those who are willing to and are capable of doing so.
No matter how skillful the trading scheme, over the long haul, abnormal returns are sustained only through abnormal exposure to risk.