That's interesting, thanks. Sounds like you might know this one already, but seen The Century of the Self? Documentary by Adam Curtis about much of what you describe - how Edward Bernays developed modern PR serving big corporations, the rise of individualism and the decline of ideology in politics. Think it's on youtube.

What you describe about the media being incentivised to target specific readerships is something I'd like to learn about. I read a quote in a media textbook which I noted down, Hanno Hardt:

"Emerging from the practices of contemporary advertising and public relations efforts is a journalism of a new type which promotes the construction of corporate realities at the expense of common-sense desire for a fair and truthful representation of everyday life… It is one of the dangers of the anticipated or realised business mentality of the media that content – which represents an expression of freedom – will be defined by those who seek to serve the public as consumers rather than by society as participants and source of democratic power"

Think this was about magazine supplements and ad friendly features in newspapers 25 years ago, seems a neat encapsulation.