People will always be there to underestimate you. Whether its what you say, or do, your attributes will end up defining you, as others underestimate you. What poses interest in my relative views, is of how much we tend to actually underestimate ourselves. We end up adding problematic views of how we see ourselves, that we believe that everything that is causing our doubts and beliefs of ourselves, is what others view of us as well.
We underestimate what we say to others, what we do, how we are.
More importantly, we underestimate who we are as a person. And that my friends, is the saddest bit of all.