Sigh... I have a pen, anyone have an envelope?
So the company's annual revenue should be in the ballpark of $65 M/yr.
The estimated cost to build the thing is $750M, and their estimated payback period is 11 years. That doesn't quite jive with the numbers I've come up with, and doesn't take into account net-present-value calculations, financing costs, operating expenses, etc. But, even so, you should certainly be able to pay for the thing over its many-decades-long lifetime.
If I had to guess, it's that they're adjusting the revenue (That 65M/yr) for inflation because it's not all going to be in today's money, but not the $750m, since that's going to be spent relatively quickly. This is entirely a guess - I don't know how businesses usually account for this - but it would close up the logical gap you're pointing out, without requiring fancy stuff.
Promising costs nothing, it's the delivering that kills you.