You are not taking into account that the Con bonus at L40 is more than your actual hps from class levels.
A level 40 character has 13,600,000gp
Consitution
base 14
inherent 5
enhancement 12
That is a Con of 31, modifier of 10, or 400 hps at level 40.
I think they can stand to blow 80 hps on...