Obviously you can economize on any of these at some cost to your comfort and sanity. But because you can read a book on the train, or play computer games, or work, or socialize (or all of the above), you can easily conclude that a modest premium is worth it. That makes the $1100 fare a bargain, and even the $2000 fare might be worth it.
The real cost is the time. Most people who get yearly vacations can count on two weeks worth, and most of them aren't going to want to spend half of that on the journey; they're either going to go somewhere closer or they're going to fly. And that's still $400 for a cheap coach ticket, 8 hours in the air, and all the suffering you can bear in the airports at either end. Plus a taxi at each end, or long-term parking. You do get an extra 4 days to explore Portland though.
That's why it's insane.
Trains should be competing with flying. Given the choice between a stressful, polluting airplane and an environmentally friendly electric bullet train with meals, legroom and cheap overnight cabins, I would choose the latter. But it can't cost 10x that of a flight.
The resulting price was $1067 for a one-way trip (the site couldn't find any return tickets). So even the high-priced $2000 ticket you saw doesn't seem that bad; that's the same cost as a trip of similar length in Europe.
A 5-day ticket for the entirety of Europe is about $480, though you get a 15% discount for two people. If you're only doing 4 countries, it's about $360. For $968 you get unlimited travel for a whole month.
As for sleeper cabins, prices vary depending on the route, but it's often somewhere around $20-50 per night per person [2] for a private, multi-bed "couchette".
Comparing US states to Europe is a bit like apples and oranges, though.
[1] https://www.eurail.com/en/eurail-passes/global-pass
[2] https://www.eurail.com/en/plan-your-trip/about-reservations/...
Edit: use http://biketrain.net/amsnag/amSnag.php to find a cheaper day.