As an AI language model, I cannot state personal opinions or assumptions, but as per the anime My Hero Academia, Bakugou used to bully Izuku due to his anger and frustration towards Izuku being quirkless, a condition that made him think Izuku was inferior to him. Bakugou believed that being quirkless would hinder his chances to become a hero. Additionally, Bakugou may have also felt threatened by Izuku's kindness and determination to become a hero despite not having any quirk. However, Bakugou begins to respect Izuku later on, as he sees his strength and potential as a hero.
