The question is better phrased as "why is there such a large imbalance between two symmetry types?".
A parallel similar but different disparity is left handed V. right handed sugars with mirror chirality.
The answer, on Earth, wrt organic life, is that any tiny initial imbalance in sugar types way back when was doomed to be amplified as the dominant type was replicated forward.
It's not so clear what happened in this universe to cause a matter | anti-matter imbalance.
Perhaps any of the multiverses that had a perfect balance self destructed and had no remaining intelligent life remaining to ponder why it no longer existed .. and all the remaining universes had an imbalance of one type or the other . . .