It has already cost a couple of billion or so and contracts are in place that would cost many millions if not a billion or so to cancel.  Make sure you look at the whole picture before assuming the cost of termination would be less than the cost to proceed.  Further, it might be wise to dig a little deeper into the pros and cons before concluding if it a good or bad project.  We cannot assume the loudest screamers are necessarily correct in their point of view.