According to Osho, the self-question persists because you seek answers outside yourself, turning living inquiry into secondhand belief. The problem and solution never meet when Krishna, Christ, or a teacher is your answer. Only by turning inward through meditation or devotion to become the answer yourself does the mind fall silent (samadhi), and then all questions, including 'Who am I?', naturally disappear.
Because you keep wearing other people's answers like borrowed shoes; only when you look inside and see for yourself do the questions stop.