I'd propose that having a great deal of pride in something you had nothing to do with is indicative of a self, and therefore a life, without meaning.
Taking that previous statement more broadly you can see there are other examples of someone having pride in something they have no control over. Shirts with sports teams names or hats with a beer brand on them, come to mind. George Carlin said it a bit differently -
“Pride should be reserved for something you achieve or obtain on your own, not something that happens by accident of birth.”
The pride you have in something you have no control over can be benign or pathological. Like so many things in life it's a matter of degree and context. Certainly being a proud Seahawk fan or member of the Sons of Norway is not some sort of pathology. This can be fun, a way to connect to other people and a way to honor and appreciate your heritage.
The pathology comes about when that pride becomes excessive and becomes a, or possibly the, defining characteristic of a human being. A person without an independent sense of self - who you are, will be blown about by the winds of culture and society. True Believers in all mass movements are those without a foundational sense of who they are. As the Country Western song goes "You've Got to Stand for Something - Or You'll Fall for Anything"
Before you take the country western singer's advice "that you've got to stand for something or you'll fall for anything" it would be wise to take heed of Nietzsche's thoughts on conviction -
"A very popular error: having the courage of one’s convictions; rather it is a matter of having the courage for an attack on one’s convictions!”
"The countless people who sacrificed themselves for their convictions thought they were doing it for absolute truth. All of them were wrong: probably no man has ever sacrificed himself for truth... It is not the struggle of opinions that has made history so violent, but rather the struggle of belief in opinions, that is, the struggle of convictions. If only all those people who thought so highly of their conviction, who sacrificed all sorts of things to it and spared neither their honor, body nor life in its service, had devoted only half of their strength to investigating by what right they clung to this or that conviction, how they had arrived at it, then how peaceable the history of mankind would appear! How much more would be known! (Human, all too Human)"
Who are these persons without a self?
I'd break them into two groups one exciting and normal the other sad and sometime dangerous.
Who's looking for a self might be another way to ask the question.
The first group is of course young people. They don't know enough about the world to have an idea of who they are or who they want to become so they try on all sorts of different identities. That's exciting and normal.
The second group is made up of people who never tried on multiple identities or explored different ways of looking at the world. They may have been raised in an authoritarian fundamentalist type family where anything other than "the" accepted identity was punished or discouraged. They may, in their search for meaning have happened upon some person, group or ideology that was so compelling that they formed an attachment without understanding why. This group is sad and sometimes dangerous. Sad because being a cleverly constructed automaton (not having a self defined by your self) is the waste of a perfectly good life, and dangerous because of the historical record of some mass movements and cults.
In ancient Greece, the temple of Apollo at Delphi bore the inscription Meden Agan (μηδὲν ἄγαν) - 'Nothing in excess'.
I pulled that quote off Wikipedia but I remember sixty some years ago or so my mom saying nothing in excess all things in moderation. My mom was a bit of dreamer I suppose. My actions and ideas in the sixties and seventies growing up were probably more from culture than mom.
But I digress. The point I wanted to make was that pride in your city, country, race, sexual orientation, religion, ancestry or any number of things you didn't make happen may be okay in moderation but becomes problematic in the extremes. All those things can be a part of your self - but none of those things can be who you are, your self. If you think they are who you are - then "you" don't exist and that is a shame.
In general it's probably advisable to not have a lot of pride in yourself. For one thing it will make you not all that likeable (for example see Donald J. Trump) and because pride is one of the seven deadly sins. I'm not trying to thump anyone with my bible - but you can find wisdom literature in various places.
Being sort of a scold I'd say that many people sacrificed to allow us the freedom available to us in our great (and sometimes not great) country. Sacrificing your self, your ability to think independently - to the mass movement, mass culture or cult and therefore giving up your freedom, you dishonor those people who fought and died so you could have freedom.
Discussing and thinking about why people choose not to be free (not to have an independent self) is an abstraction if you are referring to anyone other than yourself. You might gain some understanding for why people become possessed by an ideology but you can only change yourself.
Erich Fromm a German Jew who escaped the Nazis wrote the book Escape From Freedom in 1941. In this book he outlines three ways in which man escapes from freedom - authoritarianism, destructiveness and conformity. If you are interested in Erich Fromm this 1958 interview with Mike Wallace provides some of his thinking. Aside from the validity of the ideas Erich Fromm is talking about it may be somewhat instructive to consider that network television carried shows with this sort of intellectual depth for popular consumption decades ago and compare that with television content today.
Eric Hoffer's book True Believer - Thoughts on the Nature of Mass Movements is another good source for this sort of investigation. Eric Hoffer was sometimes called the longshoreman philosopher because he was a dock worker in San Francisco. He had no formal education but was a highly educated man. One of my heroes.
Philosophy is great and all that but what practical advice is there for developing your best self?
You could turn to a fictional work like Cormac McCarthy's Pulitzer Prize winning book "The Road". The authors page describes the book as follows -
"Through encounters with other survivors brutal, desperate or pathetic, the father and son are both hardened and sustained by their will, their hard-won survivalist savvy, and most of all by their love for each other. They struggle over mountains, navigate perilous roads and forests reduced to ash and cinders, endure killing cold and freezing rainfall. Passing through charred ghost towns and ransacking abandoned markets for meager provisions, the pair battle to remain hopeful. They seek the most rudimentary sort of salvation. However, in The Road, such redemption as might be permitted by their circumstances depends on the boy’s ability to sustain his own instincts for compassion and empathy in opposition to his father’s insistence upon their mutual self-interest and survival at all physical and moral costs."This part of the book, where the father and son are having a conversation stood out to me -
He [The Boy] sat there cowled in the blanket. After a while he looked up. Are we still the good guys? he said.So that's it - make sure you are one of the good guys.
[The Man:] Yes. We're still the good guys.
[The Boy:] And we always will be.
[The Man:] Yes. We always will be.
[The Boy:] Okay.
You could also turn to music and listen to Crosby Stills Nash and Young sing about it...