Personal net worth is kind of a fantasy number anyway as it takes into account things like endorsement deals that haven't come to fruition or stock options that haven't been cashed (and which if you were to sell might decrease the option and thus your net worth) in addition to actual assets like property. But for the last four years she's had a lot of major endorsement deals and ad campaigns so that number isn't too surprising. FWIW I found the $4 million number quoted here.
thank you for that excellent explanation; it makes sense that it's in part a "fantasy" number, and reflects those things you said.
FWIW, that table says Ashley's country is Germany, and Michelle Kwan's is England. I know where they get Germany -- Ashley was born there, even if her family left shortly thereafter. I don't know about Kwan's.