From L to R: Bill Gates, Warren Buffett, Amancio Ortega. Photo: World Economic Forum and Eldiario

$212.4 billion. 

That's the estimated net worth of Bill Gates, Warren Buffett, and Amancio Ortega, according to Bloomberg.

It's also roughly the Gross Domestic Product (GDP) of Portugal.

Needless to say, these guys are worth an incomprehensible amount of money. They each acquired their fortunes by going down different roads, but along the way, they have offered up invaluable lessons that can be applied to those of us with a fraction of their net worth.

Bill Gates: Know when to diversify
Bill Gates is the richest man in the world. He made his fortune by not only founding Microsoft but holding onto his massive stake in the business as the company's market value soared. As Microsoft's stock price went, so did Gates's wealth.

So it may come as a surprise that Gates now only owns around 4% of Microsoft. After years of riding Microsoft's stock, Gates choose to diversify his wealth, and most of his net worth is now tied up in Cascade Investment, a holding company that was formed with the cash received as the billionaire slowly unloaded his shares of Microsoft.

Gates now has large stakes in dozens of companies and is less reliant on the stock performance of Mircosoft, a company that's strategic actions are not solely within his control.

Amancio Ortega: Avoid the bright lights
Who? To most people, the name Amancio Ortega doesn't ring any bells. But for most, the store Zara will sound familar. Ortega is the man behind Inditex, the parent company of retails giants like Zara and Bershka.

Despite founding the company and being the guiding force behind its global expansion, it seems Ortega practically avoids all spotlights. It is reported that he's never had an office because he prefers to be involved in the factories or design teams. Another fashion legend, Coco Chanel, once said that "luxury must be comfortable, otherwise it is not luxury." While many wealth individuals seek the media spotlight, it's clear Ortega is comfortable and happy flying under the radar.

Warren Buffett: Don't retire
Warren Buffett is 83 years old and has been unworldly wealthy for decades. As a 20 year-old student, he learned his stock-picking brilliance from the father of "value investing," Ben Graham, and quickly became a successful investor. Buffett likely could have retired at the age of 30, but he didn't.

Buffett identified his passion early in life and never viewed his work as "work."

Around his 50th birthday, Buffett's net worth stood at roughly $260 million. Today, it sits at nearly $65 billion. That means an estimated 99.6% of Buffett's net worth was accumulated after his 50th birthday. How's that for being over the hill?

Warren Buffett's biggest fear is about to come true
Warren Buffett's $65 billion could be in trouble though. He just called this emerging technology a "real threat" to his biggest cash-cow. While Buffett shakes in his billionaire-boots, only a few investors are embracing this new market which experts say will be worth over $2 trillion. It won't be long before everyone on Wall Street wises up, that's why The Motley Fool is releasing this timely investor alert. Click here to learn more about what's keeping Buffett up at night and the one public company we're calling the "brains behind" the technology.

David Hanson has no position in any stocks mentioned. The Motley Fool owns shares of Microsoft. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.