There's many things you can do to be worth a billion dollars. It's just the people that do them rarely receive the billion dollars. The standard example is Dennis Ritchie vs Steve Jobs. Ritchie created C. Ritchie created Unix. They both died in the same month, but Jobs was the billionaire and everyone wrote a story about his passing. Ritchie was not a billionaire, he simply did the work that changed the course of human history. It's not an isolated event either. John Bardeen, Walter Brattain, and William Shockley invented the transistor, but none became billionaires.

The problem isn't that you can't do something deserving of a billion dollars. Clearly it is possible. It's just that if you do it, you rarely get the billion dollars.