One of the problems with rosy projections on programs like this is they never factor for unintended consequences. There’s a delay in acquiring a key component, maybe some of the technology does not advance as quickly as anticipated, so production has to wait for it to catch up, causing time management crises, MMT inflation jacks expenses way beyond predictions*, there are labor disputes which slow the time frame, cost overruns become critical … the list is endless, but none of it is part of the original prediction. So after cost overruns. time delays, unanticipated increases in costs, yadda, yadda, the project takes twice as long to complete (or longer) and costs twice as much (or more). I think there’s a train track in California that can be used as a typical example.
* A friendly elbow in the ribs for you,
@07pilt, my friend!