And I work with lots of people in Europe who routinely fly all the time. I'm not sure how big a "movement" it is to take trains when it doesn't make sense in terms of time and money to do so. Not to put too fine a point on it, who cares what someone with an Instagram account says?

You might, but you talk of a movement. If it's in the "movement" stage, then it is very much not an ingrained part of the culture yet, which was your original claim. Ditto for the instagram account. That speaks to something that may be grass roots, but not cultural. Further, this mindset speaks towards an ingrained bias of privilege that many/most people probably can't actually afford. Even assuming the rail cost for a 4,000 to 6,000 km trip is comparable to flight, the ability to take upwards of 3-4 days of your time to leisurely make a trip requires you to have that much leisure time at your disposal.

I just read that the Austrian national railway is planning to re-introduce them and was surprised.

Europe had a pretty decent overnight train network in the 90s and even into the 2000s.

Then flying got cheap and people basically didn't want to take those trains any longer. Most disappeared.

What, short of making flying much more expensive, would make a new attempt at introducing them successful, you think?