If they were homesick to the point that it made them resent undergrad, they're going to be even more homesick in med school, especially once you lose summer and are really limited in the time you have to go home, and especially if you're going farther away from home. Every year we would see applicants who have literally never lived anywhere but their home town, now applying to our med school that is a 6 hour drive from home. 1) how likely is that person going to come to our school given that there are a number of schools much closer to home, and 2) if they've never lived away from their families before, medical school is not the time to try doing that. That should have been done for college when there's still not that much to lose in terms of time and money if things go south, and when it's much easier to transfer (you can almost never transfer med schools, and if you're allowed, it's typically between pre-clinical and clinical years, so you still have to stick it out for a couple years)
If they didn't like any of their classes, who's to say they'll like any of their classes in med school? The first 2 years is non-stop classes, and didactics continue through clinical rotations. If they didn't like any of their professors, that's a big sign that there's something wrong with the student and not the professors.
If they didn't make any friends, one would be concerned about their social skills or ability to interact with others. Gotta be able to talk to patients and colleagues, even if you're going into pathology or radiology!
Depression and mental illness is a big factor contributing to attrition from medical school. If you went through undergrad depressed and never really got treated or addressed it, med school is going to make it even worse.
