How does someone go about getting to be one of the richest people on the face of the earth? Of course, starting out with a lot of money can make a big difference. For some of the world's ultra-rich -- like the Walton family through Wal-Mart (NYSE: WMT) or the descendants of those that founded Mars candy company -- that's exactly how it happened.

But for many others, what started as a life with either little or modest means has become something else entirely -- mostly through sweat, tears, perseverance, and -- yes -- luck. Among the world's richest people, I went out to find the 10 who had the most, but started with the least -- relatively speaking.

Here, then, are the world's ten richest self-made billionaires.