This makes Tiger Woods look kind of poor:
The very best paid of these—in fact, the best paid athlete of all time—was a Lusitanian Spaniard named Gaius Appuleius Diocle. [….] Twenty-four years of winnings brought Diocles—likely an illiterate man whose signature move was the strong final dash—the staggering sum of 35,863,120 sesterces in prize money. The figure is recorded in a monumental inscription erected in Rome by his fellow charioteers and admirers in 146, which hails him fulsomely on his retirement at the age of “42 years, 7 months, and 23 days” as “champion of all charioteers.”
His winnings are estimated to be worth $15 billion today or enough to feed all of Roman for a year.