I don't think any NIL investor at our level gets anywhere close to a positive ROI on his money. In fact, the only ones I can think of offhand at ANY level who probably DO have a positive ROI are Livvie Dunne, who is insanely popular on social media, hence has millions of followers and many advertisers, and Caitlin Clark's sponsors [only because she has become a media and social media darling]. Of current NCAA athletes, I can think of none.
But what product makes her a positive roi to advertise? If she is making her own money based on posts/activity monitization that is different and not ROI that a company would see based on paying NIL