You are what you act

If you are a fool, usually you will act like a fool, and people will treat you as a fool;
If you are not fool but act like a fool, people will still treat you as a fool.

Therefore, if you are not happy because others treat you as a fool, there mostly have 2 possibilities-

1. You act as a fool but you do not discover
In other people's eyes, you are what you act.
You may claim "image" in other's eyes may not be real, same as "image" in the mirror.
However, image come from the main body, that is YOU.
Actually, other people do not have any responsibility to identify whether your image could truly represent you.

Therefore, to "solve this problem", an "active monitor" is needed to find what act make people think you are a fool. Then, of course, get rid of such act.

2. You are really a fool but you refuse to accept

Then you should improve your thinking skill, problem solving skill, knowledge, etc, so you are not a fool anymore.