Nobody is willing to pay for trains that take 3-4 as long and are 3-4 more expensive. Maybe you are one of those very, very few people who would do that, but for the most part humans are willing to have 2h of less comfort to get somewhere.

Also, as European who has traveled a lot in train, they are not always so super comfortable over night.

Also, lets be honest, 90% of the discomfort of plane, has to do with boarding, and not plane rides themselves. Those things can be expressed relativity easily.

Building incredible expensive high speed trains across a territory as large as the USA is insane in scope and expense, and minimal in benefit. Specially with electronic planes, cars and autonomy happening.

There is also the reality that there are already huge amounts of airport infrastructure that could be activated with electric planes.

Building a high speed train network is a 30 year project, that in 30 years would be mostly pointless and unused.