Sure, maybe the top 1% is self-taught (probably not, though, you're just selecting for your point). How about the next 15%?
The examples I gave should make it incredibly clear that people can and do learn enough to get to the top of their fields without going through a formal process. It doesn't mean that you will. It doesn't mean that there are no fields with rigid credential requirements. It does mean that no formal body controls education, only schooling and credentials.
>"Sure, maybe the top 1% is self-taught (probably not, though, you're just selecting for your point)."
Another thing to think about is that with or without credentials in their past, at the very top everybody is self-taught. No business school on earth can teach Zuckerberg exactly how to set Facebook's strategy. He's got to make his own curriculum.
You have a PHD in drama? Good for you. I'd rather watch a high school drop out like Leonardo DiCaprio.
You have a PHD in computer graphics? That's nice, but once again a dropout beat you to it. He currently leads Oculus Rift.
Marketers? Salespeople? Businesspeople? Authors? Seriously... try to name even one at the very top of the game who became that way through formal schooling. It's not easy.