Not all startups invent something brilliant, and it certainly doesn't require to be a genius to get big bucks.
A decade ago I worked for a startup that developed a better product than its competitors (evolutionary, not revolutionary). It had a slightly better engineering team, more effective sales force, and more nimble org structure than its closest competitors. As a result, it went public in 2000 and got acquired in 2004. Founders and most of early employees got big bucks. Well, certainly not billions, but many millions.
So the obsession of getting rich doesn't mean the stupidity of the whole approach. It's a matter of calculated risk when joining a startup, hard work while working for the startup, and some luck.