What are you talking about? Lots of people have become very wealthy "betting on a vision before it has arrived" and "betting on what could be". Have you heard of companies called Amazon? Apple? Once a company has reached it's potential, it's "vision", then it's too late to get the full benefits from investing in them.
And by the way, Nvidia is one of the leaders in their field and actually producing quality products that are in demand...so I wouldn't exactly equate it to an old man pitching pigeon food saying buy! buy! buy! (whatever that analogy is about!)