I'd love to see the US fully mapped out with true highspeed rail, but part of the problem is the amount of time off work Americans have. We're guaranteed nothing, and a pretty good portion of us have to use vacation time for sick days. A travel option that takes longer isn't going to take off here because of that. People won't spend an extra day travelling, changing trains, et cetera, when their entire vacation is a 3 day weekend so that they only have to use one vacation day in case they have to take their kid to the doctor 4 months later.
Not even close to arguing against the trains, just saying that we need to change some other shit, too. We need better labor laws that couple with things like forced caps on flights, less subsidiaries for airlines, the tracks being nationalized, priority given to Amtrak on certain lines, and better accessibility on the trains themselves.