well, to a certain degree I can see how an American may be proud of their nation because it reminds him that many people that were in his situation achieved great things
Here in Canada one of our problems is that native Canadians commit suicide at a very alarming rate... and many of their kids spend their days and nights high/drunk/both. It seems that some level of nationalistic pride may be ok, because it would probably instill some self-esteem into the person and let them know that there is nothing wrong or inferior about them. If natives had a better understanding of their history and traditions, maybe they would be more willing to attempt to achieve.
However, everything has its limits. Particularly people of european decent who've enjoyed a privileged history don't need to go rubbing it in the faces of blacks, Filipinos or whoever... they know very well that they can achieve anything they want to because examples of successful white europeans are so abundant.
So it is a bit of a double standard, but maybe it's ok for a black person to revel in the accomplishments of say, Obama or Malcolm X or the Zulu nation... what have you.