I think Caitlin's fame has reached a point in which in her stardom transcends her sport. When was the last time we had a college athlete, in any sport, who was as big a star as Caitlin is? So, while eyeballs certainly matter, they aren't the end-all, be-all of endorsements. In another thread, I cited Shaun White and Usain Bolt as examples of athletes who compete in rarely watched sports, but became superstars nonetheless. Their stardom transcended their sport. (If I remember correctly, White's net worth today is $67 million, while Bolt's is $90 million.) Caitlin has a chance to do something similar.
I will guarantee you that Caitlin and her agent have a plan to make her a very, very wealthy woman over the next decade. It's not like she is begging for endorsement deals.