They won’t learn as much if there aren’t people to interact with in said library, to talk about what they’re reading. Some people might comprehend something a little slower than others.
I would wager money the average overly-bright kid would learn more in a library than in a classroom of other fifth graders, most of whom can’t grasp the semicolon and its varied uses, with Ms. Henderson the harried teacher, who is vaguely resentful of Bright Child’s gifts...
Depends on the student! Some are just as happy as clams not being bothered by anyone while they're learning something new. Our daughter taught herself the Japanese language by watching Anime and reading Manga in the original language and without dubbing or subtitles. I also had bought her a couple of language workbooks for grammar, learning kanji, etc. In addition to the language, she learned two different video editing programs well enough to create two music videos that reached the finals at the AnimeBoston video contest a couple of years ago.
Some folks can learn just fine on their own. They are the ones who will sit in class and doodle or daydream, and who drive their teachers crazy. My hubby, SirKit wishes he'd been homeschooled; he would have learned a lot more in high school if he'd been able to study at his own pace and not waste time doing the silly things you have to do day to day in high school.