I read that Denmark releases a list every six months of the skills and degrees that are allowed to immigrate, or get priority or something like that. From looking at the last one I assume they value education, the liberal arts and humanities a lot more than the US.

It ends up being a catch 22. When you want to leave the US because of a lack of upward mobility, social services, jobs in your field, and you can't save because of healthcare, rent, and debt, then how can you have enough money to move to another state, much less another country?

Can't answer the where at, but most likely by having an in demand skill and/or a job already lined up. Either that or they had family there. Immigration away from here is basically impossible otherwise.

They have qualifications. Or relatives. Or something of value to offer.

If you have a PhD or MD (additionally, you know, just straight money), you can emigrate to a lot of places. Probably most places.

Portugal and a lot of effort (Plus cash to invest).

Basically going through the Golden Visa process (Which has changed substantially the last year, happy to explain more if curious)