The reality is that yes, cassettes really were responsible for a substantial downturn in music revenue in the late 70s and early 80s: https://i.insider.com/4d5ea2acccd1d54e7c030000 Then cassettes got replaced with CDs which (initially) were read only, which again saved the market from piracy ... until online piracy with Napster and MP3 players completely crushed the music market, but far worse than cassettes. Even 20…
That graph does not show cassettes were responsible for that, it just shows revenue numbers. There are other possible causes. As someone who lived through part of that (I’m from ‘78 but for a country that was lagging in media developments; we got CDs in the early 90s) I can say that cassettes were a lousy medium. I love them because I grew up with my Walkman and I loved the tape swapping scene (physically compiled an…
You don't mention any of these possible causes though.
> interpreted as people willing to buy music just fine provided it sounded good and kept sounding good
Yes, CDs replaced cassettes and records. They had better audio quality and were nearly as small as cassettes. But cassettes weren't much worse overall than records. The audio quality wasn't as good as vinyl (though that came mostly from cheaper tapes, good tapes has fairly competitive audio) and aged more quickly, but they were much smaller, which was a big advantage. So overall, cassette piracy was competitive with vinyl sales, but not with CD sales.