In "Flowers for Algernon", why does Charlie say that in some ways he was better off before the operation?

With great
intelligence comes a greater awareness of the fault of everything and the greater the chance
that he is isolated or alienated. Charlie realizes that before he had no realization of the
truth of things. Ignorance was his best policy. He was not aware of people treating him
differently and did not have to worry about fitting in or becoming smarter than anyone else. He
had his routine, he did his work, he was peaceful and comfortable because he didn't know any
differently. With a greater awareness and greater intelligence, he could see what was wrong with
things and he is now the object of jealousy and resentment.