I don't think this is particularly accurate (nor timely, the reference to Gordon Bethune who retired in 2004), but demonstrative.
It does show that at a 100% load factor there is a very low return, but at the industry average of 80-85% there is a constant loss.
As some famous investment banker is often misquoted as having said: "If I'd been at Kitty Hawk, I would have shot them both"
If you want to make money in this crazy business, be a supplier not an operator.