it also (likely) doesn't take into account the massive discounts you get at scale and Apple's famously optimized supply chain. I wouldn't be surprised if the real BOM is sub 1K.
That said, with raw numbers like this I always have to think of the teardown of the Juicero which revealed that it used numerous custom parts that certainly made it very expensive to manufacture: https://blog.bolt.io/juicero/
The catch with Juicero of course is that while the parts were very expensive, it could have been made much cheaper by using standard parts instead of the custom ones. I'm not saying that's the case here but it's worth taking these things with a grain of salt.
Apple obviously had some serious discussions on this and came down on the “customize to make it the best we can” and “don’t subsidize it at all” - unlike how some consoles were done.
Even if the BOM was $1K, that’s right in line with the standard 3-4X retail price multiplier expected for hardware products.