In the Creed franchise, one of Adonis' biggest flaws is always his ego. He struggled with it in the first movie, which is why Little Duke didn't want to train him. Despite Little Duke being a family friend and the son of Apollo Creed's trainer, Duke, the coach knew Adonis' hubris would lead to his downfall.
Source：https://www.cbr.com/creed-the-next-round-adonis-daughter-amara-ego-pride/
