I would dispute 3, listening to the same genre doesn't imply you lost interest in music, because being interested doesn't comprise only of listening to the different genres. According to your definition if you listen to the same genres 7/24 your whole life, it means you lost interest in music after 30?
Listening to the same genre means that you're not as willing to search anymore. So even if you're still interested in _your_ kinds of music, you're not interest in exploring the musical landscape as much as you did -- your preferences have solidified.
But, honestly, I don't know how all this is controversial, unless someone is 20 and all their friends are too.
I'd expect anybody over 30 or so to verify that even if music is still a big deal for them, it's not as much for most of their friends as it was in their teen years and early 20s.
Unless you're 30 and all your friends are eg. DJs and techno-heads or heavy-metal fans still rocking those leather pants, the usual course is that they are more interesting in their careers, families, new babies, and binge watching TV and surfing, than following music, even if that was a big part of their identity in their teens. Is that inaccurate?
