A good reason for terrible Chinese tourist behaviour might be found in the infamous cultural revolution when Mao basically destroyed centuries of culture, tradition and values which form the core and identity of a nation.
So devoid of such a core the Chinese people can't really be called the inheritors of the China that existed for such a long period of time, they are actually children of a new country that didn't want anything from them but obedience and just limited itself to giving them the bare basics and a history that barely understands anything of it's past, besides being heavily edited to fit in the party's guidelines,
The end result is as expected with people who were raised with the lies of the regime and it's propaganda telling them they stand head and shoulders over everyone when in truth they are nothing and are worth the same amount of respect.