Whether I’m black or white has no bearing on whether I should be proud of anything outside of my own influence; I’m convinced identity politics gets us nowhere.
When you're born, you aren't just dropped out of the clear blue sky onto a level playing field fully defined by the merits of your own actions. Life isn't a lone survivor video game.
You're born in context: historically, financially, genetically, and otherwise. Some people take pride in their heritage, their lineage, their culture, their traditions, etc etc etc. Just because it isn't your cup of tea and you'd rather only celebrate what you consider to be your own accomplishments (and I say it this way on purpose because without your born context there's no guarantee that your life would've turned out as it did) does not mean everyone views the world the same way.
I think more generically you should ask yourself why it bothers you so much when people celebrate aspects of their identity.
I'd largely have no problem with "white pride" festivals if the concept even made any sense at all (which it doesn't, and which is why it's basically "white power" with a tiny PR tune up), but these "events" are basically just Klan rallies. Versus look at most pride festivals. They're full of people dancing and singing and genuinely celebrating things they have in common with one another (or in some cases, like with gay pride and ally ship, things they simply have an affinity for).