It's a charming idea, but the sheer cost of drilling a 400 miles of tunnel would bankrupt the state budget. To make something like this profitable, you'd have to move tens of thousands of people per day.  And ... you still have the problem of moving those tens of thousands TO the tunnel entry point and FROM the delivery point, neither of which is likely to be their final destination.  Kind of like standing in a long line for a short ride on the Tomorrowland Rocketship.

I wish these entrepreneurs luck, but I'd be happy just to see proven, effective, high-speed rail established between Fort Collins-Denver-Colo Springs.  That wouldn't be cheap, either ... but it will be at least a factor of twenty cheaper than this ridiculous scheme.  And somehow they manage to make it work in China, France, Japan, Germany.

Maybe I'm wrong.  But then the 1935 skeptics of flying cars by the year 2000 may have had their heads screwed on right, also.