Men whose only concern is other people's opinion of them are like actors who put on a poor performance to win the applause of people of poor taste; some of them would be capable of good acting in front of a good audience. A decent man plays his part to the best of his ability, regardless of the taste of the gallery.
Nearly all men are slaves for the same reason that the Spartans assigned for the servitude of the Persians -- lack of power to pronounce the syllable, "No." To be able to utter that word and live alone, are the only means to preserve one's freedom and one's character.