What can we learn from billionaire investors beyond how to build wealth and happiness?

That’s the question I posed to William Green, acclaimed journalist and author of Richer, Wiser, Happier: How the World’s Greatest Investors Win in Markets and Life. Over five years, William interviewed icons like Charlie Munger, Howard Marks, Jack Bogle, and Monish Pabrai. But rather than just chasing alpha, he uncovered how these billionaires navigate uncertainty, failure, and even happiness.

In our interview, we explored the surprising habits, philosophies, and mindset shifts that helped legendary investors not only build wealth but live fulfilling lives.

The Real Secret of Billionaire Investors

Many of us are tempted to think billionaire investors hold some secret stock-picking formula. But according to William Green, it’s not so much about predicting the market because, as he puts it, “the future is unknowable.”

Instead, these legendary figures thrive because they make consistent, rational decisions and avoid common pitfalls.

“If you basically avoid the really common stupid stuff,” William shared, quoting Charlie Munger’s philosophy, “and you focus on doing a few things right… you will do well. You'll be fine.”

This idea of subtraction—removing mistakes, distractions, and unnecessary complexity—is a core lesson from Richer, Wiser, Happier.

Indexing Is a Winning Strategy for Most

While many of the investors William studied ran hedge funds or managed billions, their advice for the average person is surprisingly simple.

“I’m not equipped to be one of these great investors,” William admitted. “So what I need to do is just be honest about my limitations… your default position is to say, ‘I'm just going to index.’”

Index fund investing—buying broad market funds with low fees and holding for the long-term—emerged as a powerful takeaway from his research. “For most of our listeners here, that’s just an incredibly smart decision,” he added.

Learn more about the benefits of indexing: 3 Smart Reasons for New Investors to Choose Index Funds

Start Simple, Then Stick With It

The complexity of investing can overwhelm many families. But simplicity, William emphasized, is your superpower.

“You just say, I'm going to ride that rising tide… and I’m going to do it at a very low cost.” He advises holding two index funds—one U.S., one international—and contributing monthly through tax-advantaged accounts like IRAs or 529s.

This mirrors the easy and effective strategy we’ve shared before on this blog: How to Start Investing Today in 10 Simple Steps

As William put it: “If you do that and you keep adding to the pot, you will be rich. You will be fine.”

Prepare for Uncertainty, Don't Predict It

One of the most memorable parts of our conversation was William’s discussion of Buddhist wisdom and how it shaped the thinking of investors like Howard Marks.

Marks embraced the idea of “Mujo”—the Japanese Buddhist concept of impermanence. Everything changes. Markets rise, fall, and shift constantly. The best investors learn to adapt, not control.

“When everyone is fearful, it may paradoxically be that the world is less risky,” William shared. That’s why Howard Marks famously invested hundreds of millions into the market during the chaos of 2008.

You can’t predict what’s coming next. But you can control your behavior, your spending, and your reaction to fear.

Focus on What You Can Control

William’s interviews repeatedly reinforced the power of focusing on what’s in your control. Legendary investor Bill Miller told him: “You can’t control your reputation… but you can control your intention.”

That lesson resonated deeply with me. As parents, we’re often bombarded by financial news, market fears, and social comparison. But focusing on our own plan—keeping expenses low, staying invested, and being kind to ourselves—makes a world of difference.

Even when setbacks happen (and they will), you can maintain what William called “equanimity”—a calm, centered mindset amidst the storm.

Don’t Be a Genius—Just Avoid Being Dumb

Charlie Munger’s approach to life and investing was simple: “Invert, always invert.” In other words, instead of asking, “How can I win?” start by asking, “How do I lose?”

From investing fads to leveraging debt to gambling on market timing, many investors get in trouble by chasing the next big thing. Munger believed the secret was simply avoiding “standard stupidities.”

“Focus first on survival,” William said. “If you're wrong—and even the smartest people are wrong a third of the time—you still need to survive.”

That’s where diversification and simplicity come in. Spread your investments. Avoid leverage. Think long-term. Live within your means.

Success Isn’t Just About Money

Yes, William Green wrote a book about billionaire investors. But ultimately, Richer, Wiser, Happier is about much more than money.

“Investing success is about being directionally correct and keeping at it,” he told me. “You don’t need to be number one. But if you do the right thing consistently, the results become overwhelming over time.”

The same applies to family life. Being consistently kind, honest, and intentional—day in and day out—leads to a richer, happier life.

One of my favorite takeaways was William’s daily habit of asking: “What can I subtract from my life today that isn’t helping me?” Whether it’s an app, a bad habit, or a toxic distraction, small changes compound.

As Bruce Lee famously said, “Hack away at the unessential.”

My Biggest Takeaway from William Green

After five years of research and interviews with the world's wealthiest and wisest investors, William Green distilled his biggest takeaway like this:

“The future is unknowable, and yet there are ways we can consciously stack the odds in our favor through how we behave.”

He’s not just talking about stocks—he’s talking about life. About making good choices, showing up consistently, and focusing on what really matters.

And after this powerful conversation, I’ve added a new daily mantra to my habit tracker: “Subtract something unhelpful.” Because a little clarity each day leads to a much richer life.