Indeed, a few years ago I spent a couple hundred bucks to travel from DC to LA (in a seat, not a cabin). It took 3 days and was only a little cheaper than a flight that would have taken five hours, but it was something I always wanted to do. But if it were competing on price and/or convenience, long range train travel in the US almost always loses to flights except for in the Northeast corridor (and even then its at best a tossup)
Why spend $2,500-$5,000 and your trip takes ~30+ hours when you can spend $650 and get there in a few hours via flying