"Not to say that getting rich is simply a matter of having a swell attitude. The path to riches usually involves the kind of risk that would make most people feel a little queasy. Harrison Group head Jim Taylor recently persuaded more than 3,000 pentamillionaires to discuss their path to success. Perhaps not surprisingly, none of them had a cushy union job down at the DMV. The vast majority — 80% — either started their own business or worked for a small company that saw explosive growth. And almost all of them made their fortune in a big lump sum after many years of effort."

The article mentions the other 20% is made up of heirs (10%) and fortunes from passive income / stock picking. The other 80% made it from startups. Of course, this leaves out the career ladder; don't MBAs get rich too? I don't envy them, but I know they exist, and I know they have money, as do MDs and JDs. Where do they fit in?

Also:

"Getting rich also requires a certain amount of stubbornness and clarity of purpose. Consultant Joel Kurtzman, who evaluated 350 startups for his book Startups That Work, found that successful outlets usually have a team of two or three founders who share a common vision; the success rate for this model was a remarkable 50%. The odds for solo founders were more like the oft-quoted one in 10, in part because they often found themselves working at cross-purposes with hired guns who see things differently. That's what 34-year-old Justin Jarvinen learned the hard way. The entrepreneur saw two promising business ventures go down the tubes after he took on partners who tweaked his ideas beyond recognition. But three years ago he started VerveLife, a service that helps companies promote online marketing efforts with free music downloads. Knowing that his success depended on his enthusiasm for bringing the idea to market, he carefully chose partners who supported his vision."

So, according to this article: 80% of people who get rich do so w/ a startup 50% of good teams succeed 10% of solo founders succeed