Over the past century, the United States has generated billions in wealth for the select few who came up with a brilliant business idea (or had the good fortune to inherit it).

Even as many other countries are now creating newly minted billionaires, the U.S. is still home to the many of the world's richest people. Notably, many of these people are self-made and didn't simply profit from an inheritance.

But what about the rest of the world? Who are the global financial elite? And what can we learn from their success? As you'll soon see, there are many roads to riches, but there are two helpful ingredients: ambition and lucky breaks.

Most of the people on this list have an abundance of both...

Carlos Slim
Net Worth: $73 Billion

(Note: All net-worth estimates on this list come from Forbes.)

This Mexican magnate is the child of Lebanese immigrants who managed to develop a thriving real estate business in Mexico City soon after they arrived.

That fueled an active early interest in wealth building for this mega-billionaire: Carlos Slim allegedly bought his first stock at the age of 12. (Many self-made millionaires and billionaires talk of having read The Wall Street Journal and other business publications while still in junior high).

Five years out of college, Slim had already amassed a $40 million fortune by using his investment firm to accumulate stakes in various industrial firms. Yet his real fortune was made in the 1980's when he acquired a number of major Mexican assets at distressed prices, at a time when few other major investors had excess capital to work with.

The key takeaway: Slim got off to a fast start, and then benefited from having a lot of financial liquidity at a time when local markets were in distress.

Amancio Ortega
Net Worth: $57 Billion

This son of a Spanish railway worker began working for a shirt maker while still a teenager. He would go on to open his first clothing shop, focusing on quilted bathrobes, until 1972 at the age of 36. A few years later, he opened his first Zara store, which now has branches in more than 70 countries. Zara is one of several retail brands operating under the Inditex Group, which has nearly $20 billion in annual sales.

In the crowded world of retail, how did Ortega make Zara and his other stores stand out? New items can be produced and stocked in just two weeks, thanks to local production. Rivals typically need to plan six months in advance, due to global supply chains, which means they may end up stocking items that have already gone out of fashion. This 'just in time' approach to inventory management had proven quite successful for Japanese automakers, and Ortega believed that the retail industry would benefit as well.

Ortega also shuns advertising, preferring to spend those funds on store openings and a wider assortment of choices made in smaller production runs. Other global retailers would prefer to order tens of thousands of the same item in the same size and color, and then figure out how to sell them all. That often leads to a profit-sapping strategy of price markdowns. Ortega is intensely private, and has granted just a few press interviews over the past decade.

The key takeaway: Ortega focused on quality, word-of-mouth and small production runs to avoid the high costs and bloated inventories that other retailers endure.

Li Ka-shing
Net Worth: $31 Billion

Asia's richest person also had very humble roots, working 16-hour days at a Hong Kong plastics company as a teenager. Yet by 22 years old, he was already operating his own plastics business and aggressively expanded into real estate, telecom, banking, hotels and other industries. (Some have suggested that wealthy connections through marriage explain his rapid wealth accumulation, though that is subject to debate).

Li's empire now spans more than 50 countries and employs more than 250,000 people. That vast empire grew from what Western investors think of as a Japanese-style 'Keiretsu' or Korean-style 'Chaebol,' where inter-locking ownership among various companies in disparate industries can be used to feed contracts between various entities.

The key takeaway: While many U.S. billionaires make their fortune by focusing on a specific industry, Li has sought to derive synergies across his areas of focus -- a style that is much more popular in Asia than elsewhere.

Liliane Bettencourt
Net Worth: $30 Billion

The next-richest person outside the U.S. is Bettencourt, who has a net worth of $30 billion, thanks to her controlling interest in cosmetics firm L'Oreal. As she inherited her wealth and is not self-made, we're not discussing her wealth-building approach here.

However, we will say this: Billionaires like Liliane are part of an exclusive club that has long taken advantage of a little-known wealth secret from which you can now benefit. Just as Liliane has enjoyed the advantages of wealthy relatives, there are firms with 'Rich Parent' companies, with all the benefits of those larger operations. Find out how you can enjoy the rewards here.

Bernard Arnault
Net Worth: $29 Billion

This French mogul surely had a leg up, convincing his father to sell a family-owned construction firm in 1976 and redeploy the funds into real estate. Yet his real passion was luxury goods, and over the next decade, he spent roughly $15 million to gain a stake in fashion house Christian Dior and department store Bon Marche.

Thanks to a series of legal maneuvers, Arnault was able to parlay that modest stake into a much bigger one, which was soon to be worth more than $1 billion.

By the late 1980s, he was smitten with this retail niche, eventually gaining control of LVMH, which owns such powerful (and lucrative) brands as Louis Vuitton, Moet & Chandon champagne, and Hennessy Cognac.

Today, LVMH controls more than a dozen luxury brands and design firms, many of which were aggressively capitalized by LVMH to help them grow quickly. The value of LVMH eventually grew more than 15-fold over the next 25 years. Arnault also now has stakes in supermarket chains, yacht builders and a world-class art collection.

The key takeaway: Arnault realized early in his career that luxury goods are extremely profitable, and has only acquired businesses that rank very high in terms of brand cachet and profit margins.

The Investing Answer: Few people will ever have the chance to be billionaires, but newly minted millionaires are produced on a daily basis around the globe.

Some inherit their fortunes. But many others built their fortunes themselves. These successful entrepreneurs share a few key traits: They started their wealth-building at a fairly young age, and they used their growing financial clout to buy assets that would leverage the performance of their existing investments.

Here in the U.S., the approach is quite different, as our nation's wealthiest citizens generally prefer to focus on one business or industry and deploy all of their resources to help nurture their wealth.