In general, I think it is both and sometimes neither. There are of course exceptions to everything. Some things are totally illogical. For example...

Who is PSY? A little hint...Najeneun ddasarowun in-ganjeogin yeoja
Keopi hanjaneui yeoyureul aneun pumgyeok ittneun yeoja
Bami omyeon shimjangi ddeugeowojineun yeoja
Geureon banjeon ittneun yeoja

Marketing is likely the biggest single factor. We drink Coke because we are told to drink Coke. When advertising budgets for The Coca-Cola Company were cut sales dropped by large percentages.

Who is Billy Ray Cyrus and how did "Achy Breaky Heart" become a hit? Ask Mercury Records how many millions they spent promoting the line dance and record.

Timing is a major factor. If The Chordettes were to be a new group today, would "Mr Sandman" be a hit?

It is not "kids" who buy music. It is sold to older people. Here is a pretty good article that will give you an idea of who is buying music.

https://spinditty.com/industry/Who-is-Buying-the-Most-Music-Its-Not-Who-You-Think

So...the answer to the question can not be answered by a single yes or no.

Billy

“Amazing! I’ll be working with Jaco Pastorius, Charlie Parker, Art Tatum, and Buddy Rich, and you’re telling me it’s not that great of a gig?
“Well…” Saint Peter, hesitated, “God’s got this girlfriend who thinks she can sing…”