I don’t think there’s anything inherently wrong with being proud of impersonal achievements. If one of your parents did something considered pretty great, I think it’s generally fine to be proud of it, even though you had no agency in being born to them.

As with anything, though, it’s very possible to take it to the extreme. If an achievement or value becomes your entire personality and you begin to actively disparage others on the basis of not-being-that, as you said, that’s when I call it one of the bad “-isms.”

I see nationalism as a range within that of patriotism, but starting at that extremist point.