Some of this came about during the "supermodel" era of the 80s. Although the term is overused beyond recognition to now include someone who poses for Sears catalogs, but in reality it really was naming only about 5-6 models who could command $10,000 a day including Cindy Crawford, Linda Evangelista, Christi Turlington, Claudia Schiffer, and Naomi Campbell. Obviously there have been others before and after but this was where the term gained recognition.
Along with these Supermodels came super photographers like Herb Ritts, Steven Maisel, Avedon, Patrick Demarchelier, Greg Gorman, Scavullo, Bruce Weber and others who became celebrities in their own right and started the celebrity shooter genre. Obviously there were great photographers before and after them but in my memory this was the time of the over hyped photographer being more of a celebrity than the celebrity themselves.
But as Suzanne says, the egos have been around since people started believing their own marketing materials.