I don't disagree with your analysis, but it's important to remember that most states think of the 80% of that $1.5B that isn't profit as going to their citizens in the form of local spending.
This happens to be in the same vicinity as the most popular ski resort in the state, and a number of other popular outdoor attractions.
It's not quite your average rural economy that's desperate for any sort of new business/jobs/investment.
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A mine has to be weighed against the risk it represents to their existing economy - both in actual impacts of environmental disasters, and reputational if there's any negative stories coming out about it.
Tourists don't want to go have their destination wedding in the town that's in the news regularly because of X or Y pollution, even if they can't see it and it's not a risk to them on their visit.