Steve Jobs and Steve Wozniak are the names most closely tied to Apple, one of the most valuable companies in history. But 50 years ago, when they were putting pen to paper and officially founding the company, there was a third, lesser-known signature on that document: Ronald G. Wayne.

At the time, Wayne was an engineer at Atari when Jobs recruited him to help persuade Wozniak to take the leap and build a computer company. Wayne—who later described himself as the “adult in the room”—drafted Apple’s original partnership agreement and was awarded a 10% stake, while Jobs and Wozniak each held 45%.

Just 12 days later, he walked away.

Concerned about the financial risk tied to the partnership, Wayne sold his stake back for $800 and later received an additional $1,500 to formally forfeit any future claim to the company. Today, with Apple’s market cap hovering around $4 trillion, that 10% stake could theoretically be worth more than $400 billion.

Wayne went on to spend decades working as an engineer and living a relatively quiet life—far removed from Silicon Valley—eventually settling in Nevada, where he has relied heavily on Social Security and occasionally sells rare stamps and coins.

But now 91, Wayne said he doesn’t view the decision through a lens of regret—but rather of clarity.

“My success has never been defined by money,” Wayne told Fortune in an emailed statement. “It’s been defined by acting with clarity, integrity, and sound judgment, given what I actually knew at the time. My perspective has become much clearer over the past year, as I came to understand how far the public narrative has drifted from the facts.”

In hindsight, selling his stake looks like a costly mistake. But in 1976, Apple was far from a sure bet. Jobs had taken out a $15,000 loan to fulfill the company’s first order from a Bay Area computer store—one Wayne knew had a shaky reputation for paying its bills. Unlike his younger cofounders, Wayne already had a house, a car, and personal assets he feared could be seized if the business failed.

Apple’s third cofounder’s advice for young entrepreneurs

For a growing share of young people, entrepreneurship is becoming an increasingly attractive path. Nearly 38% of graduates in the classes of 2025 and 2026 said they are considering launching their own companies, according to ZipRecruiter’s most recent Graduate Report—a trend that comes as the entry-level job market has tightened considerably.

But Wayne has a warning for the entrepreneurially minded: If something sounds too good to be true, it probably is.

“Understand exactly what you are agreeing to, particularly in a general partnership, where liability is not limited to your ownership percentage,” Wayne said. “Each partner can be held responsible for the full amount of any obligation.”

While the upside in business can be limitless, so can the downside, Wayne added.

“Understand your risk in practice, not just on paper. Have counsel,” Wayne told Fortune. “And never assume your exposure ends at your percentage, because it doesn’t.”

Still, Wayne hasn’t entirely escaped the long shadow of Apple. In fact, he’s leaned into the irony of his story. Earlier this month, he partnered with Anheuser-Busch to promote a different kind of apple: the return of Busch Light Apple, a limited-edition beer that has again sparked a viral rush among fans eager to stock up.

“Let me show you where a man’s wealth really lies,” Wayne joked in a promotional video, pointing to a garage full of beer. “Yep, still a really good investment.”