The article has a whole chapter on the reasons for the boom. Deregulation is singled out as the main culprit. Neither bank managers or the public were used to a free market for financial services, since the whole financial sector had been thoroughly controlled through a corporatist system since the second world war.

So true...I remember well that 'everybody' went 'mad'...bankers included.  There were stories of people leaving banks with plastic bags full of cash...euforia set in! Ordinary people could borrow money all of a sudden, and they did...