There has never been a time in recorded history when the rich and powerful have not needed expert advisers of some description. Biblical kings had prophets, Persian sultans had viziers, and Greek city states had the Oracle at Delphi. Even the Mafia had their consigliere. In many ways these are not vastly different to many of the single-employee consultants providing advice to CEOs and board members.
See Mahoney, J. Markham, C. Management Consultancy. Oxford University Press.