There are two types of models. One is the signaling model: individuals with higher productivity signal to the potential employer that they are indeed "great" workers by attending college. Another model is the human capital development one: students learn valuable skills in college that makes them more productive, thus, get a higher salary.

Sam is skeptical about the signaling model because he reasons that, if true, everybodywould just go to college and signal that he/she is a high productivity work (even if he/she isnot) What's the flaw in Sam's reasoning?