Most foreigners have a dated view of America - especially in terms of opportunity. When net immigration with Western Europe leveled off (or reversed) a few decades ago, it had become clear that while this was still a step up for Thirdworlders, the US offered nothing to people from developed Western countries. Their home countries have many of the same ills as us (high taxes, growing populations of unassimilated primitives, socialized medicine - after ObamaCare passed), but if they were going to end up in the same place anyway, why not stay in a country of people who share your language & diet?
What I’m getting at is the commie Catalonians would like to rule Spain’s roost, but it will not happen in the foreseeable future, hopefully.