You're right, anyone can accomplish anything at any age. I even heard one famous writer, can't remember the name now, I think it was the person who wrote Harry Potter, I heard they got published at a really old age.
The man in the documentary was wise, no doubt. But he was a frail man, honestly and you wouldn't think he was a billionaire. Perhaps it's all the the years of hustling.

However, we cannot emphasize the importance of experience enough, I think experience is something that makes a huge difference.