Federer was at number 7 in the Forbes list right before this one. He earned 90 million that year. These guys know what they are doingEmma made more than her, but it's not reflected in the rankings. These guys do NOT know about the number and size of all the endorsement deals and public TV showings etc. of these athletes. They do know how much prize money they earned from tennis down to the exact $, that's why someone like Barty is ranked very high.
If they did that for men's tennis, Federer should be in the top 3, even with almost no prize money earned from last year.