It’s not surprising, I think, that Atlas Shrugged flopped upon publication: The political climate, at least in the US, was a liberal one with strong sense of (dare I say?) collectivism.
As the pendulum began to swing into conservatism in the late 1970s, so too did right-leaning philosophies such as Rand’s begin to manifest themselves–I don’t think there is much mystery there. (One of my high school classmates in the late 1970s already had a T-shirt made up that asked “Who is John Galt?” His invariable reply to those who asked was, “Read Atlas Shrugged!” And as this was in Canada, and as we were all duly proud that “our” rock band Rush actually had name recognition, I noticed that in the liner notes for Rush’s album 2112 , chief lyricist Neal Peart acknowledged Rand’s influence on him.)
This 1970s pendulum swing also coincided with the rise of the “Chicago School” of economists exemplified by Milton Friedman, influenced by F.A. Hayek, while Leo Strauss, another University of Chicago figure, proved influential on the neocons who proliferated in the Bush II administration.
More recently, Nancy MacLean’s book Democracy in Chains has brought to light economist James M. Buchanan as an influence on right-wing tycoons, particularly Charles Koch, as the meaning of “public choice” has been spun so thoroughly that it has become an “alternative fact”; Buchanan was also initially affiliated with the Chicago School, and MacLean also notes that the their economic theories got their trial under the Pinochet junta in Chile; this included drastically re-writing the Chilean constitution to put “democracy in chains.” MacLean’s fear is that the Kochs et al. are trying to do the same in the US now.
And while Alan Greenspan didn’t become Fed chairman until the late 1980s, his ascendancy served to suggest that Randism had arrived, at least in part, around the same time as the gap between productivity and wages in the graph you have linked began to become noticeable.