If the flag of an armed enemy of the U.S. is allowed to fly over government buildings, then it implies that slavery, or at least the threat of slavery, is sanctioned by that government and can still legally exist.
A person who doubts himself is like a man who would enlist in the ranks of his enemies and bear arms agains himself. He makes his failure certain by himself being the first person to be convinced of it.
No man ever got very high by pulling other people down. The intelligent merchant does not knock his competitors. The sensible worker does not knock those who work with him. Don't knock your friends. Don't knock your enemies. Don't knock yourself.
I've had my successes and failures. I know many academics in my field loathe me. I've come to loathe them back, as it seems only polite to do so. But at heart it's absurd; we should band together against the big common enemies.