I don't think there is any one rule that applies to everybody. Some people are just very skilled at making money. Warren Buffett has said that he always wanted to be rich. Others came into extreme wealth out of dumb luck and great timing (this seems more in line with Facebook and Google). The only common thread that I see is that to be successful you have to be doing something that you are very good at. That is a lot harder than it sounds because a lot of people feel pressured to do things that they really suck at but convince themselves that they are good at.
I mean - the only difference between FB and many other social networks is that everybody happened to be on FB. Of course it takes enormous amount of skill to operate on this scale, but if all those people weren't on FB, they would be on one of those other social networks doing more or less the same thing.
But Google is different. I mean - do you even remember how people used internet before Google? Google was not just "marginally better, more popular AltaVista", it dramatically changed the way we do things online. And then it did it again with GMail. Not to forget Android (though it's not in the same league as search & email). Anyway, Google had a good deal of luck and good timing, but it was by no way "dumb".
You're way out past the point that Google became Google. Two PhD CS students worked on a research project that became a multibillion dollar company. The project was not dumb luck, but the outcome was. It is not dumb luck when a hedge fund manager raises capital and makes billions of dollars. See the difference?
