Eh, I don't think that's what was actually going on for most of the 20th century. Journalist was not a prestigious job, it was in fact done by working class people. I think. It's instead a new thing that journalism is dominated by "elites".

"How journalism became a middle class profession for university graduates": https://www.theguardian.com/media/greenslade/2009/jul/21/new...

"The death of the working class reporter": https://blog.usejournal.com/the-death-of-the-working-class-r...

The original claim I was challenging was "journalists in particular no longer find themselves in the upper middle class" -- I don't think they ever were, it's possible that MORE of them are now than previous -- as you say, even as salaries drop.