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I don't think that you can assume that students who drop out of public institutions are "unhappy" -- there are many other reasons students drop out, and statistics do not tell you what happens to those students later on. The demographics at a public university are different - so overall you may have a higher percentage of students who are married or have children, students who are military reservists, students who are employed or place high value on employment and career opportunities. A part time or summer job may turn into full time work with an offer from an employer that the student is unwilling to turn down. Public universities also tend to be far more flexible and make it easier for students to follow an on-again, off-again route to graduation - precisely for the reasons that they are serving their demographic. My guess is that the vast majority of pubic university "dropouts" have left college for financial or family reasons, with the "financial" not always referring to negative pressures.</p>