Is this every college student's greatest fear? From observation, I'd think so.
From speaking with roommates, group mates, and other younger peers, I realized that it's a gripping fear. I can't help but feel that the silence in the classrooms after lecturers ask, Are there any questions?, speaks for itself.
I used to be deathly scared of making mistakes or presenting myself as anything less than intelligent, and, boy, that certainly precluded me from so much in life. I didn't ask questions when I needed clarification, which is such an integral part of learning.
Now, after graduating from college, having worked my first full-time job, and surviving impostor syndrome, I realized that "real" adults are still figuring things out (since no one person can be a master of all the skills that a real profession requires).
Understanding the black box that was adulthood made me more comfortable with the potential of being wrong. Today, I ask questions nearly uninhibitedly (only in appropriate circumstances, of course). I'm even working on reining in the sort of thinking out loud to which I've been defaulting.
Thinking back to the question-askers of my academic past--of both "good" and "bad" questions--I'd say that they're doing pretty successfully in life.