The creation myth of American wealth is almost always rooted in the entrepreneur.

It's the two kids who start a computer company in their garage or dorm room. Or the former standup comic who creates form-shaping undergarments, or the South African immigrant who creates a new electric car and private space program.

But despite the high-profile examples, America may actually be falling behind the rest of the world when it comes to creating entrepreneurial wealth. A new study from Barclays, "Origins and Legacy: the Changing Order of Wealth Creation," finds developing countries now lead the U.S. when comes to wealth creation by entrepreneurs.

(Read More: Entrepreneur Asia: A CNBC Special Report)



Worldwide, 40 percent of millionaires (which is defined as those with investable assets of $1.5 million or more) cited a "business sale or profit" from their business as their source of wealth. Only a quarter of the millionaires cited inheritance as their wealth source.

In the U.S., only 21 percent of millionaires cited business sale or profit as their source of wealth. A much larger percentage cited saved earnings or personal investments as their sources of wealth.

