Robert Rosenkranz is a self-made billionaire. His key to success: stoic philosophy.

In his latest release, “The Stoic Capitalist: Guidance for the Uncommonly Driven,” Rosenkranz reveals how the age-old philosophies of figures like Epictetus, Seneca, and Marcus Aurelius significantly contributed to his achievements — and can do the same for you.

“In essence, this book challenges much of modern-day culture,” Rosenkranz shared with The Post. “It emphasizes self-reliance, full accountability for your life, rejecting the victim mindset, and letting go of worries about the uncontrollable.”

Set to be released on May 6th, the book offers a blend of memoir and ancient insights. At 82, Rosenkranz is a self-made billionaire with significant influence in private equity, multi-strategy hedge funds, and the insurance sector.

He retired as CEO of Delphi Financial Group in 2018, where he grew the company’s worth 100-fold.

“This is a book for anybody who aspires to live a life that gets them the distance from where they were as a child,” Rosenkranz, who grew up in a one bedroom ground floor apartment in Manhattan with his parents, said. “These are ideas you can use to realize your childhood dreams.”

He was inspired to write the book because his nieces and nephews wanted to record interviews with him about his life, but Rosenkranz, 82, insists this book isn’t an exercise in self-aggrandizing. 

“This project wasn’t just celebrating myself,” he said. “I was really trying to do something useful to give people some ideas that they could use to thrive in their own lives, which is why I framed it all in terms of cognitive theory and stoic philosophy.”

The book is spliced up into short chapters that follow his life from childhood to the present day, and include topics like getting rich slowly, how to get angry, and death and taxes.

“You could read any chapter, and they more or less stand on their own,” he said. “I just don’t feel like the Stoic principles come alive unless you see how they can be applied to someone’s life.”

Michael Bloomberg dubbed the book “an inspiring story of a life well lived.”

“I think of myself as a natural born stoic,” Rosenkranz writes. “The habits often that helped me cope as a child, and helped me succeed as an adult, echo in the philosophical insights of the Stoics.”

He says ancient Greek philosophers taught him the mastery of his own emotions.

“Stoics use reason to regulate emotions,” Rosenkranz said. “We all react emotionally. We’re not trying to deny that or suppress emotions, but it’s your responsibility to decide whether acting on emotion will serve your interests or not.”

Rosenkranz, who is Jewish, was a summa cum laude graduate of Yale’s class of 1962. He says he experienced antisemitism on campus and was told he could only work for Jewish firms upon graduation. Nonetheless, in true stoic fashion, he entitled a chapter “You Face Prejudice: So What?.”

“There were very truncated opportunities for Jewish kids when I was growing up,” he said. “I just thought this is the way the world works, and I’ve got to figure out how to adapt to it, and I think that’s just simply a much more constructive approach than sitting around criticizing the way the world works.”

In his book, Rosenkranz also shares many of his insights from decades in the business world, from how to nail an interview, to how to build wealth, to how to negotiate.

“Negotiation is a problem for two people to solve, it’s not a game for one person to win,” he explained. “It’s a creative process where you’re both trying to come up with a solution that will leave you each feeling better off.”

But he’s sure to consistently litter Stoic insights throughout, like accepting impermanence as a fact of life and learning the value of time.

“Time is our most valuable resource, but it’s so easy to fritter away your time if you’re not being mindful of it,” he said. “You can make more money, but you can’t make more time.”

Anyone who understands that insight, Rosenkranz argues, is liberated to live a life well lived.

“The Stoic concept of freedom is not license to do whatever you like, but self-possession of learning how to value and experience the fullness of time,” he writes. “Being busy is the enemy of being thoughtful.”