Leonard Riggio is the owner of Samraat, a favorite in this year's race. But he is perhaps better known as the founder and chairman of book-selling behemoth Barnes & Noble.
Born in New York City, Riggio started what would become his Fortune 500 bookstore chain in the 1960s. His first foray into horse racing happened more recently, when he decided to fill some empty horse stalls at his farm on Long Island, New York.
"My wife and daughter have both had a long-term interest in show horses," Riggio told CNBC. "We train and breed show horses, and we've had extra stalls at the farm for years, so we decided to give it a go and get into horse racing. That was about 10 years ago."
Riggio's father, a professional boxer, twice defeated future middleweight world champion Rocky Graziano in the mid-1940s, but it was an uncle who first introduced him to the sport of horse racing in his formative years, taking him to the Aqueduct Racetrack in Queens, New York.
Read MoreWhy bet on the Kentucky Derby when you can own it
"I would go with my uncle, who was a horse player," said Riggio. "He did teach me the virtues of betting small."
Relative to the wealth he's earned, Riggio joked, his investments in horse racing are "probably something like a $20 exacta box" for the average American.
While the self-made mogul describes horse racing as a "fun business" in which it's "very hard to come out ahead," he said that he may be on the verge of turning a modest profit.
He estimates that the cost of running an elite thoroughbred horse to be between $50,000 and $60,000 per year. Samraat, with winnings of more than $700,000 so far, is his top-earning horse to date.
"I think we're at the cusp of turning the corner here," said Riggio. "We're at the point where we think we can enjoy the sport, and also curtail our investments and make some money."