Obviously, that's not true. I'm a lawyer, and have met several tradesmen (electricians, plumbers) that made more money per year than I did.
But in general, most people make more over a lifetime with a college degree than without one, especially outside of the skilled trades (which often involve some college classes, in any event). For example, my sister was an education major. She couldn't find a job in the field when she graduated, so she worked in a clothing store. She was immediately made a manager, over people who had worked there for years, even though she had no experience and an unrelated college degree. Similarly, a friend in college was made the manager of the fast-food place he worked at, because he was a college graduate, over people who had worked there for longer than he did. You'll find college often helps you out, even in jobs that don't require it, to give you an edge in hiring and promotions.