Do you think people only followed MJ because he played for the Bulls?
The answer is no, of course. Sure - more Bulls fans followed him than other fans, but there were a lot of people checking his highlights.
Caitlin Clark is similar - if you check the news, they've been selling out areas when she plays because people come to see her - even if they aren't Iowa fans. WBB has higher viewership than normal due to people checking in to see her play.
From a BYU-centric perspective - I could ask you about Jimmermania. Do you think the only people who showed up to see Jimmer highlights were BYU fans? Of course not. Other people wanted to see it as well. Jimmer could've been on national ad campaigns his senior year due to the attention he was getting, for sure.
Bottom line - NIL was never supposed to be about "we want to pay you to come to the school of our choice". It was always supposed to be about "You have the right to earn money off of your name, image, and likeness".