I do not think that this is always true. I think it depends largely on the student. I also think that it does not necessarily start until maybe 5th grade or so.
To some extent, good students do have a social handicap. I assume that this is partly because they are successful and people become jealous of them.
However, I think that the personality of the student has much more to do with it. In my experience, good students (in high school) who are also socially adept do not have a lot of people hating them. It is more the student who is smart and seems to be arrogant about it (or who just has no idea how to deal with people who aren't smart) who has the social handicap.
Students who have to work unusually hard to strive for good grades in their exam subjects sometimes can become socially isolated through lack of time to meet with other students - or even members of their own families. This might be more likely to happen with students who have some form of social handicap or other challenge already. For example, a student who is not studying in his own native language may have to work twice as hard as other students. Other students may be having financial struggles to get educated and may have less time all round, due to holding down a part time job to pay college fees. Something has to give and often it is free time - the time that others use for socialising. Often if these students achieve good grades, the scarifice is thought worth it. It becomes a social handicap when it is permanent and results in avoidant behaviours.
I think that the "social handicap" element might be a bit too harsh. I would say that there is a level where students who seek to achieve at a high level are victims of social maligning. Yet, I would also suggest that all students, to an extent, are victims to this configuration. There are moments in the maturation process where students who are high achievers are compelled to believe that "it's uncool" to do well in school. At the same time, there are students who denigrate those who do well in the school setting. Yet, this is one of many crosses to bear of students and there should be some level of understanding that this dynamic is highly present in many stages of maturation and growth.
I do not think that academic success lends to social handicaps. Just because you are successful does not mean you are a social misfit. There are many students who are academically successful who are also outgoing and popular. Most schools require students to achieve good grades before they are allowed to participate in extracurricular activities. The more extracurricular activities an individual participates in the more social they can be. There is the stereotype of the school "nerd." This person is usually very smart but socially delayed. There will always be this type of person in a school, but keep in mind that this is a stereotype and should not be generalized too all students achieving good grades.
Gifted students may be the true owners of a social handicap more so than kids who get good grades.
It is a scientific fact that people who are highly intellectual have many times a hard time adjusting to their less intellectual peers, and have more problems making strong bonds and human connections because of their tendency to over-analyze, or because a high number of gifted individuals tend to become rebellious, all as a result of an overactive analytical mind that cannot be matched to another.
Contrarily, students who get good grades often do it because they do not question authority, are able to follow rules, often make connections without asking and employ those skills to test better, or complete work quicker. They maybe are more liked by teachers and peers because they do not represent a detour in everyday thinking habits. That is certainly not the case many times with gifted students who, at times out of their own will, prefer to flunk, not do work, and argue rules.
Gifted children are indeed very challenging. That is what makes their social handicap a possibility.
It varies greatly from student to student, I have found. Where many times the Valedictorian of our graduating class has a 4.0, they are often some of the most outgoing, involved students we have. There are others that have to work very hard for their grades.
A Vietnamese brother and sister who were recent immigrants and in the 8th and 9th grade, had to work incredibly hard each day to learn the language, master the subjects and get good grades. They each ended up going to MIT on scholarship, but they did have social issues in that there was never much time to just hang out with friends, go to dances or date.
For students who only work on academics, and stick to such a rigid study schedule, yes, it could be a possibility, but I don't see many of those students, especially now with Facebook and MySpace.
Some of the social handicaps I've seen include nervousness about starting conversations, or being exceptionally quiet in class, even when called on. Sometimes they have a sense of humor or behavior that is a few grades below where they are at in school.
It depends on who you're talkin about. Some people's personalities are "I'm better then you" or "I don't know how to really talk to people" these things are a small factor into lots of well off students. There a lot of good students who are well off in their grades they just have less social problems. Really good grades or not being social or out going is a matter of personality and ability to work with people who might not be as book smart as you are. There are plenty people who are very intelligent but not when it comes to tests.