In To Youth, why did Xiaobei Zhou later call himself Liu Yun?

Why don't you admit that you are Xiaobei? I think there is a deeper meaning. Ironically, the growth and life mentioned in the movie are really ironic, and each of us will become something we hate. Therefore, the comparison before and after makes the personality and youth of the characters more complete: 1. Xiaobei was not vain before, and frankly admitted that her sister sold steamed buns to earn money for her school, but now she is unwilling to face her past to maintain her self-esteem and form a contrast; Xiaobei hated lying before, and even the outbreak after being suspected of stealing was because he hated liars. Later, he pretended to be Liu Yun and told a bigger lie himself. So everyone will become what they once hated.