I call it the early adopter effect.
Some people call it riding the wave.
Most VC startups begin with a kernel of a good idea (large bubbles do as well). Now this idea is either self-supporting or supported by funding (both due to the assets of society - not that of the founder). As you are at the beginning of the wave, you ride it, and good people find their way towards you. You then hire these people for below market rates (most equity is worthless) and then use them to make you into the great success that you are.
There are no barriers to entry to becoming a "founder". You just have to be there, and be ready. The competition is low at the beginning. Hence you get drop outs who go on to succeed. The success is not because of themselves, but because of the situation around them.
Own all the land in America 400 years ago, and it's worthless. Wait a few generations and your descendents are some of the richest people on the planet. The founders of America look like absolute geniuses today, when it was the work of the millions who came after them that made them look like gods.
The world isn't about people. It isn't about societies. It's about complex systems, undergoing transformations with a nearly infinite number of variables, and where the slightest changes in any one of them can lead to vastly different results.
1000 possible billionaires are born everyday. Most die in the third world. The remainder come from low socioeconomic backgrounds. Cuts that to about 100. Of those 100, few are located in places like Silicon Valley. Now you are around 10. Of these 10, some go study medicine/law/engineering and disappear from the pool. Down to 1-2. Most of these guys fail.
You only hear about the successes - not the failures. The world is really fucking complex. Randomness is by far the greatest factor in people's lives.
But people want reasons damn it! There must be a secret, right?
Sigh.