Answered on Quora:
Of course, it can only mean that you have above average intelligence. I have no idea at what IQ level people start actively and frequently commenting, often in stunned or disbelieving terms, about how smart you are. But I’ve been hearing it forever. I’m at 147. I’m sure people say it to those lower on the scale too, but I’m not sure the level on which people quit remarking on it.
Based on my experiences, I would say that if most people you meet are remarking about how smart you are, you probably have an IQ of at least 120, in the upper 10% of the population. Any lower and you are getting so much closer to average intelligence that most folks would not be commenting on how bright you are. People only say things like that if you’re quite a bit smarter than most people.
Now why you have a high IQ but think you are stupid I have no idea. You don’t give yourself enough credit for your gifts.