Certainly, joining a start-up as an employee "to get rich" would be the wrong idea. But I imagine many of us here are founders, and though we're not doing our start-ups for the sole purpose of getting rich, the fact that it's a possibility is certainly important. Would you bother working on your start-up if you knew for sure that it would never make you more money than you could make burger-flipping? (directly or indirectly)