Las Vegas is the 38th largest economy in the US, and the 30th largest population center. The economy of LV is larger than that of NOLA, of SLC, of OKC, of Memphis, and of RTP. It's an easy lowbrow dismissal to talk about slot machines, but an LA-LV line probably makes as much sense (cost-adjusted) as SF-LA.

One point that's easy to miss is that big-city smaller-city pairings can be uniquely economically productive. For instance, an actually-functional HSR between Chicago and STL would allow companies to easily set up satellite offices on either side of the line, taking advantage of the lower cost of living on the smaller side and the larger market and commercial network on the larger side.