Higher education isn't for everyone, and people have a variety of paths to choose from once they graduate from high school. They might know from the start that they want to go straight to the professional world. Other new graduates often decide to try college for a semester to see how it goes and then realize it's not for them.
While the decision to pursue a degree or to enter the work force is fraught with pros and cons, earning a lot of money isn't. Not that money means everything, but wouldn't we all like to see some bigger numbers on our next paycheck? You can find jobs in many industries that don't require formal degrees, but you still need relevant experience, skills and possibly other training, depending on the position.