FJ, I can empathize with you and what happened, and it shouldn't have. I do live in "Pennsyltucky" as Mercury called it, but it's not quite redneck enough where just going to college is a beatable offense... although I think a satchel might attract some hoots depending on the guys in question. When I was growing up, early in school "smarts" were actually admired. It was later in school (starting in middle) where braniacs were picked on, but as long as you weren't presumptuous about it or acted like you were better -- i.e., talked down to earth and were fun to be with -- people eventually by high school either let you alone or were positively inclined. At that point, people were also veering into their own career paths -- a lot of vo-tech in my area, then community college, and then a minority of college prep.
Guys definitely did not want to be seen as "fags" though. I'm not sure what it was. It might have even been less the sexual connotation than just the idea that the guy was weak, girlish, effeminate, not tough or strong, a real "priss" in their eyes. Yet one of my friends in hs, a pretty flamboyant queer, never really seemed to get beat up. It was like they didn't consider it worth their time because he was SO overt. maybe it's the ones who were more in the middle who were considered threatening... or maybe they thought they could "save" somehow.
Honestly, based the situation you describe, I'm more inclined to think they're partly just bored with their lives, resentful that you're doing something that might bring in money, education represents 'liberalism' to some forms of conservative america and so you're getting lumped in with those sorts of political values, etc. They did it because they could, and because they are unhappy with their lives, and because there were a number of them, and because they wanted to take out their frustrations on someone. They're bullies.