They don't have fully reusable rockets in production yet. They just reuse the first stage. Even with that alone, they are the cheapest launch provider by a sign

They don't have fully reusable rockets in production yet. They just reuse the first stage. Even with that alone, they are the cheapest launch provider by a significant margin, which is why they've captured such a large share of the market. At this point it seems pretty plausible that if they succeed in making a whole rocket reusable at a decent cadence, instead of throwing away an upper stage with each launch, then costs will drop dramatically.