I'm honestly wondering why those planes are so expensive. If it's mostly human work, 1.2 billion is (very) roughly 1000 highly-skilled people employed for two f

I'm honestly wondering why those planes are so expensive. If it's mostly human work, 1.2 billion is (very) roughly 1000 highly-skilled people employed for two full years. This feels out of proportion, even for bleeding-edge technology. Does someone here know a bit more about the breakdown of costs?