The "it's not economical" argument is used very often for numerous topics and it always begs the question: not economical compared to what? Is the purportedly more economical choice accounting for every externality it creates? Is it only economical because it already exists? Are there reasons we should stop doing the economical option? Lastly, what unaccounted for benefits might materialize if the uneconomical choice was pursued anyway?

So in this particular situation, we're comparing the costs of building and operating high speed rail lines in the US to maintaining highways, hundreds of thousands of vehicles, airports, and planes. We should also account for the externalities created by using this infrastructure, so a shitload of carbon emissions plus the negatives of car culture and flying is just an awful experience.

We should also consider what may happen if high speed rail was built anyway. I bet there would be so much more medium distance travel, people would be going on day trips to cities they wouldn't have considered before. Previously unknown and forgotten areas of the country may be revitalized. Who knows what cool stuff could happen.

Anyway, it really sucks when people use the "iT,s nOt eCoNoMiCaL" argument because it's probably not true when everything is taken into account.

I think only very few people would argue for a fully connected continental network. But as you said, up and down the coast is a very good usecase for high speed rail and it's a shame you don't have any yet.

For what it's worth, in terms of urban development some of the big cities do move forward. I think that's often overlooked when mocking the US for its car dependency. (But it will take a long while until the dependency debt is paid off)

Imagine if the US joined the rest of the civilized world and built cities that aren't 99% unlivable suburban hellscape

It is possible to build trains/stations in lightly populated areas and have modern building codes in place to encourage modern, efficient towns be developed around them.

China took it to an extreme in one situation but it's entirely possible on smaller scales.

There are plenty of routes out there that are economical. I wouldn't expect one national system, but I would expect a series of state and regional systems similar to California's planned system or the Northeast Corridor.