To be honest I don't either. But I'd read where an artist in New York sold an NFT of his work for over a million dollars. Regardless if you consider them 'collectable', or even 'investments', the money is there. For this application, I consider them a way to directly pay athletes just for being athletes, so why I agree it makes more sense for a bigger name to garner such attention, it doesn't mean that NFT's of any athlete couldn't be marketed.
Regardless, this is just one avenue of many revenue streams available to this generation of athlete. It's not as 'old school' as sitting down to do an autograph signing, or a meet and greet public appearance. That seems like a lot of hassle compared to someone marketing something for them, or monetizing their social media accounts.