Chameleon's backstory is tragic and not a petty excuse - Secrets of Scroll explains how Mantis and Viper became masters. They had to prove themselves by defeating Boar along with the others. In Secrets of Furious Five too, Crane is mocked for his skinny legs and taken seriously only when he passes the test. Even Po was seen as a nobody by the others because he had no visible talent like claws, an agile physique or wings. China is a huge country and variations can exist, right ? Not everyone gets the same treatment and kung fu is an art that should be taught by masters. If masters reject you then learning kung fu is not a piece of cake. Apart from mocking her for size, the masters called her "lowly" and "not destined for kung fu" and I don't see how that is not tragic. Despite her rejections, Chameleon did self-train because in the final fight with Zhen she uses her own style of combat with tail and tongue and not her stolen skills. But of course self-kung fu won't give you power and respect, the reasons why she wanted to learn kung fu. To use it as a medium for power and respect. So she turns to sorcery as another medium, to rule with fear.