Lady Bracknell said this in "The Importance of Being Earnest" by Oscar Wilde because she represents the upper class and values societal norms and etiquette. By saying that only people who can't get into society speak disrespectfully of it, she is emphasizing the importance of maintaining social hierarchy and decorum. Lady Bracknell believes that those who criticize or disrespect society are likely either jealous or unable to be a part of it themselves. This statement reflects the elitism and class-consciousness that permeate Victorian society, which Wilde satirizes throughout the play.
