I would go to Stanford. Sure, she could go pro and make a boatload o monies, but what if she were to get injured quickly and could no longer compete? The network that Stanford will open up to her will be worth a lot, even if it can’t be quantified in the same way a pro contract.
I have no idea what she wants to do with her life, but I have a feeling that being an Olympic star will make her a favorite at her alma mater, the kind of person that gets favors/recommendations/introductions. That will be worth it. Nearly every job I have gotten has been off a referral or recruitment because of the people I knew. You can’t quantify how powerful that is in the long run.