How do you arrive at costs like that? A 787 wouldn't be much more than $120K? That equates to circa $480 per seat (250 seats) or $640 per passenger to break-even at 75% one way which is in the ballpark of the sorts of fares charged.
Apples and oranges, the fixed annual cost of a private jet are spread out over far fewer hours then an airliner.
You can't just translate operating one into another.