Why is being proud of your ethnicity considered racist?

It is not "politically correct" for everyone to get along. There is political power in divisiveness on whatever grounds: skin color, languages, economic status, religious beliefs, gender, etc. People will "generally" treat each other with same tolerance and respect that is accorded to them. It is Government that promotes hatred and suspicion of people who "aren't like us"! Sadly, people fall for Government tactics and efforts to keep folks divided.