edit: oops I noticed the other comment I replied to wasn't you, but anyway - https://news.ycombinator.com/item?id=36629620
I would argue it's just one more convenient assumption that leads us away from a realistic estimation.
It seems to me USD 2500 is an idealistic best case scenario.
edit: oops I noticed the other comment I replied to wasn't you, but anyway - https://news.ycombinator.com/item?id=36629620