Why do some white people have to water down every non white culture globally?

Not sure what the question means. You're saying they go overseas and diminish the importance of the native culture? That's just old colonialism and imperialism, thinking their culture is legit and everyone else's culture is backwards and savage. But ultimately, the culture of colonialism and imperialism is the most backwards and savage thing. I don't think it's as true today though, however, in America, Americans tend to water down global culture, like Mexican and Chinese food, bc it's like the lowest common denominator. You have to cater to everyone, so you can't have authentic Chinese food that Arabs or blacks might not like, so you have to make it more plain and boring.