Imagine that some cultures do things that you consider horrible (e.g. genital mutilation, “honor” killing, killing people for blasphemy or sexual orientation, etc.). Your culture doesn’t do that.
But my culture also does things that I consider horrible that other cultures don’t do! (SCNR.)
But my culture also does things that I consider horrible that other cultures don’t do! (SCNR.)
Also, the bad things my culture does are “near” (both metaphorically and geographically), and the bad things other cultures do are “far”.
Which I guess is why I am not a nationalist.
But I can imagine a situation that could change it, such as seeing a foreign minority doing their horrible stuff in my neigborhood.