Exactly. The non-EU migrants to the EU have to go through a lot of paperwork and it takes a lot of time. And if you then leave without naturalizing (which for m

Exactly. The non-EU migrants to the EU have to go through a lot of paperwork and it takes a lot of time. And if you then leave without naturalizing (which for most non-EU citizens is probably going to take over 10 years from the day of arrival, not to mention the daunting requirements to actually achieve it in most of the EU), you’ll likely have to through the same paperwork again, because “permanent residence” is only permanent if you remain a resident. For example I’m a permanent resident in the UK (under the EU settlement scheme, post-Brexit), but I haven’t lived in the UK for 2 years now. So in 3 years my status there will lapse. I can go back now, but I won’t be able to in 3 years. And I have it easy. Permanent resident status (ILR, or indefinite leave to remain, as it’s called in the UK) lapses in 2 years for people who didn’t gain it under the EU settlement scheme. I went back to my home country precisely because I knew that it’s no big deal for the next 5 years. I wouldn’t have left if I knew that I’d have to return within 2 years. I would have naturalised, and maybe then. Which, again, costs a lot of money, takes a lot of paperwork, and takes a lot of time. (Which, again, is easy for me, because my home country allows you to hold multiple citizenships. That’s not the case for everyone.)